Three cars were destroyed in East Orange Friday morning as the result of an underground transformer fire, officials say.

An East Orange police officer also suffered minor injuries when he was struck by a vehicle while patrolling the area. He's expected to be OK, News 12 New Jersey was told.

News 12 was told a school was evacuated as a precautionary measure due to the fire on Summit Street and North Munn Avenue.

Some residents told News 12 they heard an explosion, but that was apparently manholes popping from the underground pressure, according to East Orange Public Safety Director Maurice Boyd.

“In most cases, the manholes give way because of the pressure being released from the manholes because of the transformer being underground,” Boyd said.

Drone 12 captured footage above the cars as flames took over. Firefighters allowed the fire to burn because of electrical concerns while making sure surrounding buildings and homes were safe.

The cause of the fire has not been determined.