Tennessee officials said that a CSX train car that was transporting dangerous material derailed and caught fire in the eastern Tennessee. The incident happened in the middle of the night and forced the evacuation of several thousands of people.

The officials said that the fire was still on during Thursday noon. Firefighters have been unable to reach the burning car because of the heat, they added.

Blount County Mayor Ed Mitchell said in a statement that there were some concerns that the fumes from the fire contained cyanide, a byproduct of burning the chemical acrylonitrile, which was leaking from the train car.

Mitchell said the smoke stopped by 6 pm. Blount County firefighter Kermit Easterling said in a statement that about 5, 000 people in the area were forced to evacuate the area.

A manufacturing plant, Denso Manufacturing, was closed down on Thursday morning because of its proximity to the derailment, Blount County firefighter Kermit Easterling said.

Officials said that firefighters have been trying to keep the rail cars cool. They have also been trying to move them away from the flames.

The damaged car was carrying liquid acrylonitrile, a hazardous material used in multiple industrial processes including making plastics. The liquid is flammable and is dangerous if inhaled.

The EPA said breathing acrylonitrile can cause headaches, dizziness, irritability and rapid heartbeat.

Nearly 52 people were treated at Blount Memorial Hospital in Maryville, and 25 were admitted, hospital spokesman Josh West said. None of the patient suffered life-threatening injuries, but were experiencing respiratory issues, skin irritation and nausea, West said.