( CNN ) -- The insurgents who attacked an Afghan military base where Prince Harry is deployed may have gotten onto the base by sneaking through a hole in a fence , a British military source said Monday . Officials discovered the hole after the attack , the source said , adding that the attackers -- daringly disguised in U.S. Army uniforms -- also tried to blow up parked NATO aircraft with hand-held improvised explosive devices . Prince Harry was about a mile and a half away from Camp Bastion when the attack happened , according to the source . The royal was immediately placed on lockdown , as were other troops who were not fighting the insurgents , the source said . U.S. Marines , British forces and a U.S. Army unit that just happened to be nearby spent nearly three hours battling the insurgents , the source said . NATO releases details of brazen raid on base in Afghanistan . `` This was a well-coordinated and complex attack that we 're taking very seriously , '' a U.S. official said Monday . It 's extremely rare for Afghan insurgents to use U.S. uniforms in their attacks . The last time CNN can identify was more than two years ago , when NATO repelled attacks on two bases in Khost province in August 2010 . No coalition troops were killed in that attack , NATO 's International Security Assistance Force said at the time . At least two U.S. Marines were killed in the brazen strike late Friday , and six jets were destroyed , the ISAF said . Well-trained , well-rehearsed fighters carried out the sustained assault in Helmand province , the ISAF said . About 15 insurgents organized into three teams penetrated the base 's perimeter fence and did considerable damage , destroying six refueling stations and damaging six aircraft hangars . Slain Marine predicted his own death . The attackers toted automatic rifles , rocket-propelled grenade launchers and suicide vests . They destroyed six AV-8B Harrier jets and damaged two others before the attack ended , the coalition said . Fourteen of the fighters were killed , and one was wounded and captured , the ISAF said . Eight coalition military personnel and one civilian contractor were also wounded . It is too soon to say whether the attackers had `` inside knowledge , '' ISAF spokesman James Graybeal said . The ISAF would not say how the attackers got the uniforms , but CNN staff who have spent time in Afghanistan say they are for sale in markets there . There has been at least one other case of Afghan insurgents wearing U.S. uniforms , in May 2010 . And in Iraq five years ago , there was a dramatic and successful raid using the tactic . Attackers wearing what appeared to be American uniforms were responsible for the kidnapping and killing of five U.S. soldiers in Karbala , Iraq , in 2007 . Prince Harry is an Apache helicopter pilot based at Camp Bastion , but the British Ministry of Defence categorically rejected reports in Sunday 's British press that he was just a few hundred yards from the gunbattle . NATO admits killing civilians in Afghan strike . Harry , a grandson of Queen Elizabeth II and third in line to the British throne , `` was in no way in any danger '' during the latest attack , ISAF spokesman Maj. Martin Crighton said earlier . On Saturday , the ISAF said the camp is secure and the strike would not `` impact '' air and ground operations . Camp Leatherneck , the U.S. side of the base , was not affected by the attack , said Maj. Adam N. Wojack , an ISAF spokesman . The joint base is in a remote desert region of Helmand , the southern province in the Taliban heartland . The Taliban said it carried out the strike , calling it a response to the anti-Islam film stoking anger among Muslims . Yet Crighton said there had no organized demonstrations outside its gates before the assault . Afghanistan has seen only relatively small and peaceful demonstrations against the film during a week in which there were protests across predominantly Muslim countries and other locations . 4 NATO troops killed in 'insider ' attack in Afghanistan .
Attackers , disguised in U.S. Army uniforms , tried to blow up NATO aircraft , source said . Score: 7 Prince Harry was about mile and a half from attack , source says .