SEATTLE (AP) — The U.S. Army has identified the three soldiers who were killed when two helicopters collided in Alaska while returning from a training mission. The helicopters were headed to Fort Wainwright from a mission in the Donnelly Training Area. They crashed at about 1:40 p.m. Thursday about 50 miles east of Healy. The U.S. Army announced Friday that it has grounded aviation units for training. Twelve soldiers have died within the last month in helicopter crashes in Alaska and Kentucky. Killed in Thursday’s crash were Chief Warrant Officer 3 Christopher Eramo, Chief Warrant Officer 2 Kyle McKenna and Warrant Officer 1 Stewart Wayment.