GARNER, N.C. (WNCN) — A fire destroyed a mobile classroom at a Johnston County school Friday night, officials say.

The blaze started at a mobile unit at Polenta Elementary School, which is along Cleveland Road east of McLenore Road.

The fire was caused by an electrical problem in the unit’s HVAC heat strips, according to Todd Sutton, chairman of Johnston County School Board of Education.

The fire department was able to contain the fire from spreading to other units.

However, the fire, which was reported around 7:30 p.m., destroyed the mobile unit involved, Sutton said.