A North Carolina official says that reports of an active shooter at a school in the southwestern part of the state turned out to be a malfunctioning water heater.

News reports quote Pender County Emergency Management Director Tom Collins as saying that noise from the water heater was mistaken for the sound of gunfire at Topsail High School Friday morning. The earlier report of shots fired provoked a massive response by law enforcement and caused the school district to reroute buses and put schools on lockdown.

Capt. James Rowell, of the Pender County Sheriff's Office, was quoted as saying in local reports that deputies swept the school but found no evidence that any shots had been fired.

He said deputies did find an HVAC unit that was malfunctioning and making sounds similar to gunshots.

The incident comes less than two days after a gunman opened fire on a crowd inside a country music dance hall in Thousand Oaks, California. The gunman, a Marine veteran, killed 12 people before turning the gun on himself.