Helicopters and a bomber attacked insurgents massing in eastern Afghanistan under cover of darkness and killed more than 30 of them, the U.S.-led coalition said Tuesday. Reconnaissance aircraft spotted «large groupings» of insurgents armed with heavy machine-guns and rocket-propelled grenades on Monday night in Khost province, the coalition was quoted as saying by the Associated Press. «After positively identifying the insurgents, coalition forces engaged them with attack helicopters and a close air support bomber, killing approximately 33 of them, » spokesman 1st Lt. Nathan Perry said. An Afghan army officer said the clash began when Taliban attacked coalition and Afghan forces patrolling in Tani, a district on the border with Pakistan.