The sun rises over the White House in Washington, Saturday, May 16, 2015. The Pentagon says U.S. commandos have mounted a rare raid in eastern Syria, killing the Islamic State commander in charge of oil... (Associated Press) 
 
 BEIRUT (AP) — U.S. commandos mounted a rare raid into eastern Syria overnight, killing a senior Islamic State commander in a firefight, capturing his wife and rescuing a Yazidi woman held as a slave, the Pentagon said Saturday. 
 
 Defense Secretary Ash Carter announced the raid, identifying the militant as Abu Sayyaf. He said no U.S. forces were killed or injured in the operation. 
 
 A U.S.-led coalition has been striking Islamic State militants in Syria since last year, but this is only the second time troops have carried out a ground raid. A previous operation was aimed at rescuing Americans held hostage by the group. 
 
 Syrian state media earlier reported that Syrian government forces killed at least 40 IS fighters, including a senior commander in charge of oil fields, in an attack Saturday on the country's largest oil field -- held by IS. 
 
 It identified the commander as Abu al-Teem al-Saudi. The name indicates he was a Saudi citizen. 
 
 It was not immediately clear why both Syria and the U.S. would claim a similar operation in the Omar oil field. The U.S. has said it is not cooperating with President Bashar Assad's government in the battle against the Islamic State group. But it has always said it gives the Syrian government a heads up on operations within its borders. 
 
 The Britain-based Syria Observatory for Human Rights confirmed an oil field attack, saying at least 19 IS members, including 12 foreigners, were killed. The group did not say who carried out the attack. 
 
 A statement from the U.S. National Security Council said Abu Sayyaf was a "senior ISIL leader who, among other things, had a senior role in overseeing ISIL's illicit oil and gas operations -- a key source of revenue that enables the terrorist organization to carry out their brutal tactics and oppress thousands of innocent civilians." 
 
 "He was also involved with the group's military operations," it said. 
 
 It said President Barack Obama authorized the operation upon the "unanimous recommendation" of his national security team. 
 
 The statement also said the commandos rescued a young Yazidi woman "who appears to have been held as a slave" by the slain militant and his wife. IS militants captured hundreds of members of the Yazidi religious minority in northern Iraq during their rampage across the country last summer. 
 
 The extremist group controls much of northern and eastern Syria as well as northern and western Iraq. It has control of most of the oil fields in Syria, which are a key source of its funding. It has declared a caliphate in the territories under its control and governs them under a harsh version of Islamic law. ||||| (CNN) U.S. Special Operations forces killed a key ISIS commander during a daring raid in eastern Syria overnight Friday to Saturday -- securing intelligence on how the terror organization operates, communicates and earns money, U.S. government officials said. 
 
 The ISIS commander, identified by his nom de guerre Abu Sayyaf, was killed in a heavy firefight after he resisted capture in the raid at al-Omar, U.S. Defense Secretary Ash Carter said in a statement. 
 
 The officials identified Sayyaf's captured wife as Umm Sayyaf, an Iraqi. She is now being held in Iraq. 
 
 The U.S. government did not release Sayyaf's real name. 
 
 The ground operation was led by the Army's Delta Force, sources familiar with the mission told CNN. There were about two dozen members of Delta Force involved, sources said. 
 
 Delta Force entered the target area on Blackhawk helicopters and V-22 aircraft, a U.S. official familiar with the operation said. ISIS fighters defended the multistory building from inside and outside positions. 
 
 Abu Sayyaf was killed as he "tried to engage" U.S. troops, the official said. 
 
 Carter said he had ordered the raid at the direction of President Barack Obama. All the U.S. troops involved returned safely. 
 
 National Security Council spokeswoman Bernadette Meehan said Obama had authorized the raid "upon the unanimous recommendation of his national security team" and as soon as the United States was confident all the pieces were in place for the operation to succeed. 
 
 "Abu Sayyaf was a senior ISIL leader who, among other things, had a senior role in overseeing ISIL's illicit oil and gas operations -- a key source of revenue that enables the terrorist organization to carry out their brutal tactics and oppress thousands of innocent civilians," she said in a statement. "He was also involved with the group's military operations." 
 
 Abu Sayyaf was a Tunisian citizen, a senior administration official said. 
 
 A U.S. official with direct knowledge of the intelligence and the ground operation said Sayyaf had expertise in oil and gas and had taken an increased role in ISIS operations, planning and communications. 
 
 "We now have reams of data on how ISIS operates, communicates and earns its money," the official told CNN, referring to some of the communications elements, such as computers, seized in the raid. 
 
 A young woman from the Yazidi religious minority was rescued. 
 
 "We suspect that Umm Sayyaf is a member of ISIL, played an important role in ISIL's terrorist activities, and may have been complicit in the enslavement of the young woman rescued last night," said Meehan. ISIL is an alternative acronym for ISIS. 
 
 Meehan said Umm Sayyaf was being debriefed about ISIS operations, including any information she may have on hostages held by the terror group. 
 
 Abu Sayyaf and his wife were suspected to be involved in or have deep knowledge of ISIS hostage operations, a U.S. official with knowledge of the operation told CNN. A team from the FBI-led High Value Interrogation Group is expected to interrogate the wife, the source said. They will seek to figure out what she may know about the capture, movement and treatment of hostages. 
 
 But Michael Weiss, author of "ISIS: Inside the Army of Terror," said Abu Sayyaf was largely unknown to close observers of the organization. 
 
 Weiss said he's skeptical the United States would risk lives to capture the head of ISIS's oil operations. ISIS hasn't made significant money from captured oil fields since U.S. bombers began striking its infrastructure, he said. 
 
 A Pentagon spokesman confirmed in February that oil is no longer a main source of revenue for ISIS. 
 
 But risking American lives to capture Abu Sayyaf makes sense to Derek Harvey, a former U.S. Army colonel, intelligence officer and the director of the Global Initiative for Civil Society and Conflict at the University of South Florida. 
 
 "The most important thing about the raid is not getting Abu Sayyaf; it's getting his records," Harvey said. 
 
 Harvey asserted that Sayyaf was one of ISIS's top financiers, with likely access to the group's contacts with banks, donors, Turkish and Lebanese business interests as well as links to criminal and smuggling networks. 
 
 Harvey said Sayyaf had undeniable value as a target because ISIS is also a business. 
 
 "They're meticulous record-keepers," he said. 
 
 Meehan's statement added that Obama is "grateful to the brave U.S. personnel who carried out this complex mission as well as the Iraqi authorities for their support of the operation and for the use of their facilities, which contributed to its success." 
 
 Meehan said the U.S. did not coordinate with nor advise Syria in advance of the operation. 
 
 "We have warned the Assad regime not to interfere with our ongoing efforts against ISIL inside of Syria," she said, adding that the "brutal actions of the regime have aided and abetted the rise of ISIL and other extremists in Syria." 
 
 Airdrop, firefight 
 
 There is reason to believe that Abu Sayyaf may have been in contact with ISIS leader Abu Bakr al-Baghdadi, sources familiar with the operation told CNN. 
 
 Although he was not taken alive, U.S. forces did capture some of his communications equipment, the sources said. 
 
 More details are starting to emerge of how the overnight raid deep in ISIS-controlled territory was carried out. 
 
 Delta Force was part of a multi-branch force of about 100, the sources told CNN. There was hand-to-hand combat during the operation, which was helicopter-borne, the sources told CNN. 
 
 The U.S. forces blew a hole in the side of the building, entered through the hole and encountered more ISIS fighters, the source said. 
 
 ISIS combatants tried to use human shields, but U.S. troops managed to kill the fighters without hurting the women and children, the official said without elaborating. 
 
 One of the Blackhawk helicopters took a couple of rounds of fire but was airworthy and took off, the source said. 
 
 The U.S. forces had an Arabic interpreter with them. They came across ancient artifacts in the building, including coins, which they are examining now, the source said. 
 
 About a dozen ISIS fighters were killed in the firefight at a residential building in Deir Ezzor, the sources said. A senior administration official told CNN the purpose of the mission was to capture the target, but he engaged U.S. forces so was killed. 
 
 Meanwhile, the Syrian Observatory for Human Rights, a London-based monitoring group, said at least 19 ISIS militants had been killed by coalition bombing targeting ISIS' location in al-Omar oil field in eastern Deir Ezzor. 
 
 Preliminary information indicates that the U.S.-led coalition airdropped forces following the bombardment, it said. 
 
 There are six oil and gas fields in Deir Ezzor, all of which fell into ISIS hands in July last year. They include al-Omar oil field, Syria's largest oil facility. 
 
 Computer records 
 
 Abu Sayyaf is not a name familiar to many ISIS watchers and may well be a pseudonym. Sources familiar with the operation said he also was known by the names Abu Muhammad al Iraqi and Abd al Ghani. 
 
 But the fact that the United States clearly had him under close watch and was ready to put its forces at risk to carry out a ground raid, rather than ordering a drone strike, suggests the target was seen as very valuable. 
 
 CNN National Security Analyst Peter Bergen said the decision to send in U.S. Special Operations forces into Syria was unusual, but not unprecedented. 
 
 "Taking out the guy who runs effectively the most important financing stream is obviously significant, but what's really significant is the computer records and all the materials that he would have with him as the head of this financing arm, if indeed that is the case that he is really that important," said Bergen. 
 
 The potential to seize valuable intelligence material and documents may have been what led the U.S. government to opt for a high-risk ground operation rather than a bombing mission, he said. 
 
 Such targeted operations push ISIS to be more careful about how they organize themselves and run their operations, he said. "They are going to be looking over their shoulder." 
 
 Interrogation of Umm Sayyaf may also yield valuable information. 
 
 For weeks, unconfirmed reports have been circulating that al Baghdadi was seriously injured in an airstrike back in March in northern Iraq. That has led to speculation over who might emerge as his successor if he is incapacitated. 
 
 Iraqi authorities have said Abu Alaa al-Afari, his top deputy, and a senior ISIS security figure named Akram Qirbash were recently killed in an airstrike. 
 
 ISIS advance in Ramadi 
 
 The U.S. operation comes at the same time as a monthslong fight for the key central Iraqi city of Ramadi appears to be going ISIS' way. 
 
 JUST WATCHED Critical Iraqi city Ramadi under assault from ISIS Replay More Videos ... MUST WATCH Critical Iraqi city Ramadi under assault from ISIS 01:57 
 
 The Islamist extremist group captured the police headquarters, the Ramadi Great Mosque and even raised its trademark black flag over the provincial government building, sources said Friday. 
 
 The ISIS push began Thursday, with armored bulldozers and at least 10 suicide bombings used to burst through gates and blast through walls in Ramadi, according to a security source who has since left the city. Dozens of militants followed them into the city center. 
 
 Iraqi and allied forces have fought back, with a number of coalition airstrikes targeting ISIS assets around Ramadi, in Anbar province. 
 
 On Saturday, ISIS fighters pulled out of key parts of Ramadi, including the main buildings in the middle of the city, according to two Iraqi security sources in the city who did not want to be named because they're not authorized to speak to the media. 
 
 ISIS controls a huge swath of territory across Iraq and Syria, where it is chief among the opposition groups fighting to unseat long embattled Syrian President Bashar al-Assad. ||||| Breaking News Emails Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings. 
 
 / Updated 
 
 U.S. Special Operations Forces killed a senior leader of ISIS overnight Friday during a rare and risky ground raid in Syria and freed a young woman who was enslaved in his compound, the White House announced Saturday. 
 
 American Delta Force commandos took off from northern Iraq in Blackhawk helicopters and Osprey aircraft, going deep into ISIS-controlled territory with no allies on the ground. Their target, SIS leader Abu Sayyaf, did not go down quietly. 
 
 The preplanned operation near the eastern Syrian city of al-Amr was supposed to be a snatch-and-grab mission to capture Abu Sayyaf alive. Instead, he was killed amid an intense fire fight and hand-to-hand combat between ISIS militants and the Army Delta Force commandos. 
 
 Twelve enemy fighters were killed in the operation, while no American forces were hurt, U.S. officials said. 
 
 As the Special Operations Forces departed, they took Abu Sayyaf's wife, Umm Sayyaf, who is also considered to be an ISIS operative, into custody. As the helicopters departed, they were struck by heavy ground fire but not disabled and were able to depart the area safely. 
 
 The mission is the first known American commandos operation inside Syria outside of a failed attempt to rescue hostages held by ISIS last year. 
 
 Umm Sayyaf is being held in Iraq and will be secluded from other prisoners, officials told NBC News. She is accused of being "directly complicit in (ISIS) activities, specifically human trafficking," an official said. 
 
 The White House's National Security Council confirmed Umm Sayyaf is being "debriefed." 
 
 "We are also working to determine any information she may have regarding hostages — including American citizens who were held by (ISIS)," spokeswoman Bernadette Meehan said in a statement. 
 
 In addition, Friday's operation "also led to the freeing of a young Yazidi woman who appears to have been held as a slave by the couple," the White House said. 
 
 Abu Sayyaf was in charge of overseeing ISIS's oil and gas operations, which provide crucial revenue for the militant group that has conquered swaths of Syria and neighboring Iraq. Iraqi authorities supported Friday's raid. 
 
 A U.S. military official described the mission, which was met with heavy resistance from ISIS, as a "hugely successful operation” and represents a “significant blow” to the terror network operating in Syria and Iraq. 
 
 "Despite the rhetoric, (ISIS) is suffering significant losses in leadership and the ability to conduct operations," the official told NBC News. "Through strikes in Iraq and Syria, the Kurdish offensive in northern Syria and military successes in Iraq, (ISIS) is desperate." 
 
 The United States is leading a coalition in a military campaign to roll back the jihadist group whose self-declared caliphate in Syria and Iraq has reshaped the region. 
 
 In the Iraqi city of Ramadi, U.S.-led air strikes forced ISIS to withdraw from a government building over which the group's black flag had flown on Friday. Were it to fall, Ramadi would be the first major city to be won by ISIS since an effort by Iraqi security forces and paramilitary groups to push it back began last year. 
 
 In Syria, the group fought Syrian government forces for control of the ancient city of Palmyra, an attack that has raised fears its UNESCO World Heritage site could meet the same fate as monuments destroyed by ISIS in Iraq. 
 
 While Washington is working closely with Iraq in the fight against ISIS, it has shunned the idea of cooperating with Syrian President Bashar Assad, who it says has lost legitimacy to rule and must leave power. The United States said it did not warn Assad in advance or coordinate with his officials over Friday's special forces raid. 
 
 IN-DEPTH 
 
 SOCIAL 
 
 — Kristen Welker, Richard Engel, Jim Miklaszewski and Courtney Kube 
 
 Reuters contributed to this report.
– Last night, US Special Operations attempted to capture a senior ISIS commander and his wife in Syria. The rare raid didn't go as planned. Secretary of Defense Ash Carter today said that Abu Sayyaf fought back and was killed; the US troops involved were unharmed. They did manage to capture wife Umm Sayyaf, who is being held in Iraq. CNN notes that "Abu Sayyaf is not a name familiar to many ISIS watchers." Carter gave context: "Abu Sayyaf was involved in ISIL's military operations and helped direct the terrorist organization's illicit oil, gas, and financial operations as well." NBC News reports that a young Yazidi woman had apparently been enslaved by the couple; she was rescued. The raid, which took place in al-Amr, was carried out on orders of the president, which were given on the "unanimous recommendation" of his national security team. The AP notes this is only the second time troops have carried out a ground raid in Syria. A previous operation was aimed at rescuing James Foley and other Americans held hostage by the group.