ISAF: 4 coalition troops killed in attack involving Afghan police The U.S.-run Camp Leatherneck in Helmand province, shown in a 2010 photo, is part of the joint base attacked Friday. The attack occurred early Sunday in southern Afghanistan, an ISAF spokesman says It's the latest suspected attack in which Afghan forces turn on other Afghan or coalition forces On Friday, insurgents dressed in U.S. Army uniforms attacked a joint coalition base 2 U.S. Marines and 14 insurgents were killed in that assault, according to ISAF (CNN) -- In yet another suspected green-on-blue attack, attackers dressed as Afghan police killed four coalition troops early Sunday in southern Afghanistan, a spokesman with NATO's International Security Assistance Force said. ISAF spokesman James Graybeal didn't offer more details, beyond saying that the troops died "following an insider attack involving Afghan police." Such an assault is the latest in a series of incidents in which members of Afghan security forces have been suspected of turning their weapons on coalition or Afghan soldiers. And violence has been particularly rife in southern Afghanistan, which is considered the Taliban heartland, since a U.S.-led force first went into the country after the September 11, 2001, terrorist attacks. This includes two deaths in the south of Helmand province's Nahr-e Saraj district announced Saturday by the British Defense Ministry. In that attack, a man wearing an Afghan police uniform fatally shot two members of the 3rd Battalion at a checkpoint, according to Maj. Laurence Roche, a spokesman for Task Force Helmand, said in a statement released by the British defense ministry. This occurred the same day that another British soldier died in in a separate incident in Nahr-e Saraj, according to the UK defense ministry. This troop was killed when the vehicle in which he was riding in struck a bomb. And overnight Friday, a joint U.S.-British military complex in the same area was attacked by a band of insurgents dressed in U.S. Army uniforms, ISAF reported. Two U.S. Marines and 14 insurgents died in the "sustained" fighting during that attack, according to ISAF. The Taliban claimed responsibility, saying the strike was in response to the anti-Islam film stoking anger across the Muslim world. Yet ISAF spokesman Maj. Martin Crighton said there had no organized demonstrations outside its gates before the assault. The attack started just after 10 p.m. Friday when about 15 insurgents -- organized into three teams -- waged an assault on the airfield of a complex that includes U.S.-run Camp Leatherneck and British-run Camp Bastion, where Army Air Corps Captain and British royal Prince Harry is stationed. The attackers toted automatic rifles, rocket-propelled grenade launchers and suicide vests. One of their teams was able to breach the perimeter fence, at one point, according to ISAF. The insurgents inflicted considerable damage around the base, including destroying six AV-8B Harrier jets and damaging two others. Six aircraft hangers suffered damage, while six refueling stations were destroyed. The violence ended after coalition troops killed all but one of the attackers. The lone survivor was wounded and taken into custody, ISAF said. Eight coalition military personnel and one civilian contractor were also wounded. An ISAF statement detailing the attack gave no indication how the insurgents might have obtained U.S. Army uniforms. Earlier Saturday, 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, Maj. Adam N. Wojack, an ISAF spokesman, told CNN. Harry, the grandson of Queen Elizabeth II and third in line to the British throne, "was in no way in any danger" during the latest attack, Crighton said. CNN's Chris Lawrence, Jessica King, Joe Sterling and Greg Botelho contributed to this report.