MORE school violence: 4 stabbed, attacker killed at California university

Authorities are investigating a motive. Warnke said the knife contained a blade that was eight to 10 inches long.

Merced County Sheriff SWAT members enter the University of California, Merced campus after a reported stabbing in Merced, Calif., Wednesday, Nov. 4, 2015. An assailant stabbed five people on the rural university campus in central California before police shot and killed him, authorities said Wednesday.  (Andrew Kuhn/Merced Sun-Star via AP)

MERCED, Calif. (AP) — A male college student burst into a morning class at a California university with a hunting knife Wednesday and may have killed his intended victim if not for the heroic intervention of a construction worker who ran into the room to break up the attack.