A U.S. Army sergeant was killed and three soldiers were wounded when a mortar accidentally exploded during a training exercise in Panama, the U.S. Southern Command said. The command identified the dead man as Sgt. Ray Baker, 24. He was listed as being from Ohio, but no hometown was given. The three injured servicemen were not immediately identified. The accident occurred when an 81-millimeter mortar accidentally exploded at the El Emperados training camp. All four men belonged to the U.S. Army’s 87th Infantry Regiment, 5th Battalion.