NEWTOWN, Conn. — The shooter at Sandy Hook Elementary School forced his way into the school Friday morning and gunned down his victims using a semiautomatic rifle, inflicting multiple wounds to all 20 small children, the state’s chief medical examiner said Saturday evening.

Autopsies showed Adam Lanza, 20, did all of his killing with the .223 caliber Bushmaster rifle, not the two 9 mm handguns also found inside the school. Early reports said the handguns were used in the shooting and the rifle was found in his vehicle outside the school.