The U.S. system for checking suspicious travelers and airport security came under new scrutiny Sunday after an alleged terrorist bent on destroying a jetliner was thwarted only by a malfunctioning detonator and some quick-thinking passengers. 
 
 An apparent malfunction in a device designed to detonate the high explosive PETN may have been all that saved the 278 passengers and the crew aboard Northwest Flight 253 on Christmas Day. No undercover air marshal was on board and passengers subdued the suspect, Umar Farouk Abdulmutallab, 23, of Nigeria. 
 
 Abdulmutallab was hospitalized with burns from the attack and was read an indictment filed Saturday in federal court in Detroit charging him with attempting to destroy or wreck an aircraft and placing a destructive device in a plane. He was released from the hospital Sunday to the custody of federal marshals, who would not reveal where he was being held. But his lawyer said he was being held at a federal prison in Milan, Mich. 
 
 Adding to the airborne jitters, a second Nigerian man was detained Sunday from the same Northwest flight to Detroit after he locked himself in the plane's bathroom. Officials reported that he was belligerent but genuinely sick, and that, in an abundance of caution, the plane was taken to a remote location for screening before passengers were let off. 
 
 Investigators concluded he posed no threat. 
 
 In November, Abdulmutallab had been placed in a database of more than 500,000 names of people suspected of terrorist ties. But officials say there was not enough information about his terror activity that would have placed him on a watch list that could have kept him from flying. 
 
 'Sacrificing himself' 
 
 Officials said he came to the attention of U.S. intelligence last month when his father, a prominent Nigerian banker, reported to the American Embassy in Nigeria about his son's increasingly extremist views. 
 
 CNBC's Erin Burnett reported in Abuja, Nigeria, that family members had told her that Abdulmutallab's father had told embassy officials in a letter that his son had spoken of "sacrificing himself." 
 
 Still, in appearances on Sunday talk shows, Homeland Security Secretary Janet Napolitano said the traveling public "is very, very safe." 
 
 "This was one individual literally of thousands that fly and thousands of flights every year," Napolitano said. "And he was stopped before any damage could be done. I think the important thing to recognize here is that once this incident occurred, everything happened that should have." 
 
 Even so, airport security and intelligence played no role in thwarting the plot. Abdulmutallab was carrying PETN, also known as pentaerythritol, the same material convicted shoe bomber Richard Reid used when he tried to destroy a trans-Atlantic flight in 2001 with explosives hidden in his shoes. Abdulmutallab is alleged to have carried the explosive in condom-like pouches attached to his body. 
 
 Despite being in the database of people with suspected terrorist ties, Abdulmutallab, who comes from a prominent and wealthy Nigerian family, had a multiple-entry U.S. visa. It was issued last year. 
 
 Napolitano said Abdulmutallab was properly screened before getting on the flight to Detroit from Amsterdam. 
 
 Reviewing detection systems 
 
 The administration is also investigating aviation detection systems to see how the alleged attacker managed to get on board the Northwest flight in Amsterdam with explosive materials, White House spokesman Robert Gibbs said. 
 
 Video: Would-be bomber’s family speaks out No other flights were known to have been targeted. However, Gibbs says federal authorities took precautionary steps "to assume and plan for the very worst." Napolitano said there is no indication yet Abdulmutallab is part of a larger terrorist plot, although his possible ties to al-Qaida are still under investigation. 
 
 The United States is reviewing what security measures were used in Amsterdam where he boarded the flight. 
 
 "Now the forensics are being analyzed with what could have been done," Napolitano said. 
 
 Additional security measures are in place at airports around the world that are likely to slow travelers. Napolitano advised getting to airports earlier. 
 
 Congress is preparing to hold hearings on what happened and whether rules need to be changed. 
 
 "It's amazing to me that an individual like this who was sending out so many signals could end up getting on a plane going to the U.S.," said Sen. Mitch McConnell of Kentucky, the Republican leader in the Senate. 
 
 On Saturday, two Middle Eastern men thought to have been acting suspicious aboard a flight bound for Phoenix were detained and questioned by federal anti-terrorism authorities before being released. That incident — and Sunday's incident in Detroit — led the Council on American-Islamic Relations to urge airline security personnel to avoid ethnic and religious profiling. 
 
 Gibbs appeared on ABC television's "This Week," NBC's "Meet the Press" and CBS' "Face the Nation." Napolitano spoke on CNN's "State of the Union" as well as on NBC and ABC. McConnell appeared on ABC. ||||| Federal officials and police are interviewing a Nigerian man, who allegedly tried to "explode" a powdery substance aboard a Northwest flight from Amsterdam to Detroit, injuring himself and two other passengers, law enforcement officials said. 
 
 The man said he was directed by al Qaeda to explode a small device in flight, over U.S. soil, ABC News has learned. Authorities have no corroboration of that information, and the credibility of the suspect's statements are being questioned, officials said. 
 
 The suspect was identified as Abdul Farouk Abdulmutallab, 23, who according to federal documents is an engineering student at University College of London. 
 
 He was flying from Nigeria to the United States for a religious seminar, according to his entry visa, which was issued June 16, 2008 and was good until June 12, 2010. 
 
 Play 
 
 The government had no immediate plans after the incident to raise the threat level, a federal government source said. The threat level has been at "orange" since 2006. 
 
 The suspect had been in a law enforcement-intelligence database but was not on the government's no-fly list, according to a law enforcement official. 
 
 "The subject is claiming to have extremist affiliation and that the device was acquired in Yemen along with instructions as to when it should be used," a federal situational awareness bulletin stated. 
 
 Stay Up to Date on the Latest Travel Trends from ABC News on Twitter 
 
 Delta spokeswoman Susan Chana Elliott said that "as the plane was getting ready to land" in Detroit "a passenger caused a disturbance" by trying to ignite what was initially reported to be firecrackers. 
 
 The man was "subdued immediately," Elliott said. Northwest is a wholly owned subsidiary of Delta. 
 
 "There was one guy, who sat on the other side, the right side of the wing because this was on the left side of the wing, and he jumped over the other people and he took care of it," said passenger Peter Smith. 
 
 The suspect told authorities that he had explosive powder taped to his leg and used a syringe of chemicals to mix with the powder that was to cause explosion. This is of concert because it is a method of mixing that is consistent with terror techniques. 
 
 Northwest Airlines flight 253 -- operated on a Delta airplane -- landed safely in Detroit at 11:53 a.m. The man, who flew from Nigeria to Amsterdam and then Detroit, was taken into custody at the Detroit airport and was interviewed by authorities there. He was then taken to an area hospital to be treated for burns. 
 
 An in-flight emergency was declared when a fire indicator light when on in the cockpit, according to the Federal Aviation Administration. The pilot asked for airport rescue and firefighting services, and for law enforcement to meet the flight at gate, the TSA said. 
 
 It is unclear how powerful the explosive could have been and what the man's intentions were. Initial reports were that fireworks or firecrackers had gone off on the plane. 
 
 The man suffered second-degree burns, which is consistent with a small fireworks device, police sources said. 
 
 One of the passengers is being treated at the University of Michigan Medical Center in Ann Arbor, according to hospital spokeswoman Tracy Justice, who was not sure if it was the suspect or one of the other passengers. 
 
 Man Tried to Ignite Explosives on Plane, Law Enforcement Says 
 
 Federal Bureau of Investigation Special Agent Sandra R. Berchtold from the Detroit office confirmed that the FBI was at the airport, but she would not comment further. 
 
 "All passengers have deplaned and out of an abundance of caution, the plane was moved to a remote area where the plane and all baggage are currently being rescreened," the Transportation Security Administration, which handles aircraft and airplane safety, said in a statement. "A passenger is in custody and passengers are being interviewed." 
 
 The aircraft was an Airbus A330-300, twin-engine jet carrying 278 passengers. 
 
 President Obama was notified of the incident by his military aide between 2 p.m. and 2:30 p.m. Detroit time or 9 a.m. in Hawaii, where the Obamas are vacationing, according to White House spokesman Bill Burton. 
 
 The president subsequently convened a secure conference call with John Brennan, his Homeland Security and Counter-terrorism adviser, and Denis McDonough, acting chief of staff for the National Security Council. 
 
 Obama then instructed that "all appropriate measures be taken to increase security for air travel." 
 
 "The President is actively monitoring the situation and receiving regular updates. There is currently no change to his schedule," Burton said in a statement. 
 
 TSA has a layered approach to security that the agency says allows it to surge resources as needed on a daily basis. 
 
 It would not give specifics except that it has the ability to quickly implement additional screening measures including explosive detection canine teams, gate screening, behavior detection and other measures "both seen and unseen." The TSA said these measures are designed to be unpredictable, so passenger should not expect to see the same thing at every airport. 
 
 The Department of Homeland Security said Secretary Janet Napolitano has been briefed on the incident and is closely monitoring the situation. 
 
 The agency, which includes the TSA, said passengers may notice additional screening measures put into place to ensure the safety of the traveling public on domestic and international flights. 
 
 "As always we encourage the traveling public to be observant and aware of their surroundings and report any suspicious behavior or activity to law enforcement officials," the agency said in a statement. 
 
 Shortly after the 9/11 terrorist attacks, Richard Reid, a British citizen and al Qaeda operative, tried to blow up an American Airlines flight from Paris to Miami with explosives hidden in his shoe. 
 
 Passengers on the flight complained of smelling smoke shortly after the meal service, and Reid was found trying to light a match. He was subdued by other passengers on the plane and the flight was diverted to Boston's Logan International Airport. 
 
 Reid, the so-called shoe bomber, pleaded guilty to terrorism charges in January 2003 and is serving a life sentence at a federal prison in Florence, Colo. His actions, in part, are why we must all now take off our shoes as part of the airport security screening process. 
 
 "Eight years after Richard Reid attempted to blow up an airliner with explosives hidden in his shoe, today's incident, on Christmas Day, is a disturbing reminder that the terrorist threat is still very real and that we must continue to be vigilant and alert," U.S. Sen. Susan Collins, R-Maine, the ranking member of the Senate Homeland Security Committee said in a statement. 
 
 "The White House is calling this an attempted terrorist attack," Collins added. "It raises some serious questions, such as how was this person able to bring an explosive substance aboard a commercial airliner? And what is the Transportation Security Administration doing to address this type of threat?" 
 
 With reports from Matt Hosford, Pierre Thomas and Steven Portnoy.
– Authorities have taken a Nigerian man into custody after he reportedly tried to ignite a powdery substance—initially reported as firecrackers—aboard a Northwest jet that landed in Detroit from Amsterdam today. The man told federal officials he had links to al-Qaeda and wanted to blow up a plane over the US, reports ABC News, though his credibility is in question. He and two others on the plane were injured in the incident, and the 23-year-old suspect is being treated for minor burns. "The subject is claiming to have extremist affiliation and that the device was acquired in Yemen along with instructions as to when it should be used," said a federal bulletin obtained by ABC. A counter-terrorism official tells NBC that the plane's crew subdued the man when he attempted to light the powder as they were preparing to land. The suspect told authorities that he had the powder taped to his leg and tried to ignite it with a syringe of chemicals.