SLIPPERY ROCK — A malfunctioning heating unit Wednesday afternoon caused smoke to circulate in Allegheny Valley School on Rebecca Lane.

There was no damage to the roof, but firefighters were called to determine the source of the smoke, Slippery Rock chief Ken Taggart said.

The call came in at 12:50 p.m. according to Butler County Emergency Services Records.

All the staff and students were out of the building by the time firefighters arrived. No one was hurt, Taggart said.

Grove City, Pine Township, Unionville and Harrisville departments assisted. They cleared the scene after about one and a half hours.