U.S. military planes and troops were scouring Afghanistan's daunting Hindu Kush mountains Tuesday for six Americans who were aboard an aircraft that went missing over the weekend. It was unclear if the cargo plane had managed an emergency landing despite the tough terrain. Efforts to locate the aircraft, which carried three crew members and three soldiers, were hampered by heavy snow. "We don't want to go premature and say that it has crashed," spokesman Maj. Mark McCann said. "Until we can get a search team into the area, we are hoping for the best." The plane took off on Saturday from the main American base at Bagram, north of the capital, Kabul, but never reached its undisclosed location or any other airfield.