( CNN ) -- Four NATO troops were killed Sunday in an attack believed to involve Afghan police in southern Afghanistan , officials said , in what appears to be the latest incident of local forces turning their guns on coalition partners . The troops died `` following an insider attack involving suspected Afghan police , '' said Jamie Graybeal , a spokesman with NATO 's International Security Assistance Force . No more details were provided . The attacks followed news that insurgents disguised in U.S. Army uniforms carried out a coordinated assault Friday at a joint American-British base in the same region . That assault raised concerns that the attackers had inside knowledge . ISAF : Insurgents wore U.S. Army uniforms . It is too early to conclude whether the attackers had `` inside knowledge , '' Graybeal said . The incident is under investigation . The international coalition released details that suggest it was a well-coordinated assault on the fortified base in a remote desert region in Helmand province . Two U.S. Marines and 14 insurgents died in a firefight . The lone surviving insurgent , who was wounded , was taken into custody , the international coalition said in a statement . The insurgents -- organized into three teams -- waged an assault on the airfield of the joint base that includes American-run Camp Leatherneck and British-run Camp Bastion , where British royal Prince Harry is stationed . Six AV-8B Harrier jets were destroyed and two others were damaged , international forces said . Six aircraft hangers suffered damage , while six refueling stations were destroyed , it said . The international coalition gave no indication how the insurgents obtained U.S. Army uniforms . NATO denies civilians killed in air strike . The Taliban have claimed responsibility for the attack , calling it a response to the 14-minute movie trailer `` Innocence of Muslims '' that sparked protests in more than 20 countries . The trailer , which depicts the Prophet Mohammed as a child molester and ruthless killer , has roiled the Muslim world , . In Afghanistan , the Taliban have called on insurgents to step up attacks against the United States and its NATO allies in retaliation . Two British troops were killed Saturday when an Afghan police officer opened fire on them at a checkpoint in Helmand province 's Nahr-e Saraj district , the British Defence Ministry said . Meanwhile , the international coalition declined to release details about the nationality and location of the attack that killed four troops in southern Afghanistan . Those deaths , including the two killed Saturday , raised the number to more than 50 coalition troops killed in `` green-on-blue '' or `` insider '' attacks in Afghanistan this year . `` Green-on-blue '' refers to a color coding system used by the military , in which blue refers to the friendly force , in this case ISAF ; and green refers to allied friendly forces , in this case Afghan National Security Forces . CNN 's Chelsea J. Carter , Chris Lawrence and Joe Sterling contributed to this report .
The Taliban targeted suspected Afghan police , an official says . The nationalities of the troops killed are not immediately known . On arrival , two British soldiers are killed by an Afghan police officer .