(SBT24/7News) Plymouth firefighters have returned from Plymouth Speedway, 11631 12th Road, after a controlled burn there sent black smoke billowing into the air Tuesday, frightening neighbors.

Plymouth Fire Chief George Cook said crews were dispatched at 1:21 p.m. to the racetrack where, "they were burning something that was creating lots of black smoke."

Location was the track’s infield, Cook said. Responders decided to let the pile of undetermined materials burn itself out since they did not know the entire content of materials that were in the burn pile.

Cook said the materials included items recently used in a demolition presentation at the track, including a camper or motor home.

"We didn’t put it out, or it would have been a worse mess," Cook said. He said workers at the speedway were using heavy equipment to break up the piles as firefighters returned to the Plymouth Fire Department Tuesday afternoon.

Cook also said that the Indiana Department of Environmental Management was notified of the burn for possible investigation.

A phone message left with the track was not immediately returned Tuesday afternoon.