DALLAS (AP) — The blood stains have been removed. So has most of the debris. But some remnants of the blast that ended Micah Johnson's deadly police ambush in Dallas remain at El Centro College: a wall and door frame blown back several feet, and wires and metal dangling from a ceiling with no tiles.

Officials at the downtown community college on Tuesday showed reporters the damage left after Dallas police deployed a remote-controlled robot with about 1 pound of the explosive C4, set it off and killed Johnson early on July 8.