A student shot and killed an assistant principal and seriously wounded two other administrators at a high school Tuesday, officials said. The student was arrested.

Campbell County High School Assistant Principal Ken Bruce was fatally wounded in the chest in the shooting at 2:11 p.m. He died soon after at a LaFollette hospital, authorities said.

Principal Gary Seale was shot in the lower abdomen, and Assistant Principal Jim Pierce was shot in the chest. Both were listed in serious condition late Tuesday at University of Tennessee Medical Center in Knoxville, hospital spokeswoman Lisa McNeal said. Pierce had been in critical condition earlier in the day.

"I don't know what he was thinking or what his motives were," Sheriff Ron McClellan said of the suspect, who was said to be 15. The youth was grazed in the hand by a bullet fired from his .22-caliber handgun during a scuffle with the administrators and an unidentified teacher who helped wrest the gun away, McClellan said. No other students were injured.

"He is a big jokester. He is rowdy," schoolmate Courtney Ward, 17, said of the suspected gunman. "But I just couldn't see him doing this."

Authorities said they were unsure whether the suspect would be charged as a juvenile or an adult.

Classes at the 1,400-student school were canceled for the rest of the week.

"This situation could have gotten much worse. It did not because our staff followed the [emergency] plan in place," said Mark Wells, vice chairman of the Campbell County Board of Education.

At Campbell County High School near Knoxville, the principal and an assistant principal were wounded. The 1,400-student campus was briefly locked down.