MERCED, Calif. — A construction worker who ran into a California university classroom to break up what he thought was a fight is being hailed as a hero for preventing a student armed with a hunting knife from possibly killing his intended target. The attacker was later killed by police.

Byron Price, 31, was working on remodeling a waiting room at the University of California, Merced campus when he heard a commotion Wednesday and rushed to check on it.

The violence left Price and three others injured, but all are expected to survive. The assailant, described as a college student in his 20s, was shot and killed by campus police as he fled the scene.

“I really believe he’s a hero here. I think he prevented this first student from dying,” Merced County Sheriff Vern Warnke said. “The cops on campus, oh my gosh, praise them because they stopped a threat, but this first guy, he stopped a death.”

Two of the injured had to be airlifted to nearby hospitals, and the other two were treated on campus. Authorities didn’t release the name of the assailant or his victims.

The incident began when the assailant used a knife to stab two people in a second-floor room around the start of an 8 a.m. class, Warnke said.

“He didn’t go in knowing that there was a stabbing taking place. He went in thinking there was a fight,” Warnke said.