WYTHEVILLE, Va., Dec. 23 (UPI) -- A gunman with explosives who had held hostages for about eight hours at the Wytheville, Va., Post Office apparently has surrendered, police said. The man rolled himself onto the street in a wheelchair and was lying on the ground on his stomach as about 20 officers wearing shields approached him, WSLS-TV, Roanoke, Va., reported Wednesday night. State Police Sgt. Mike Conroy said three hostages have emerged from the building and officers were checking to make sure nobody else was inside. Police exercised caution because "we don't know what he had," Conroy said, The Wytheville...