Two U.S. helicopters that made emergency landings during a day of violence in volatile southern Afghanistan were hit by fire from insurgents, a U.S. military official said Monday. Five U.S. soldiers and an Afghan army soldier were injured when the helicopters, both involved in the same combat operation, made hard landings on Sunday _ one in Kandahar province and one in neighboring Uruzgan province. "Both helicopters received enemy fire,"said Lt. Col. Laurent Fox, a spokesman for the U.S.-led coalition force. Fox told a news conference that it was apparently the enemy fire that forced the helicopters to make emergency landings. He said the pilots saved lives by landing the helicopters after taking fire. All six soldiers were treated and have returned to duty, Fox said. He was quoted as saying by The Associated Press that an unknown number of militants were also killed during the combat operation, in a mountainous area.