Northwestern Indiana officials say a freight train hauling tanker cars loaded with crude oil partially derailed in East Chicago after dozens of the cars disconnected from the rest of the train.

Officials say 41 tanker cars somehow became disconnected Wednesday evening from the CSX train’s conductor car, resulting in the derailment of several cars.

Hazardous materials teams were sent to the site, but officials say no oil was spilled, and no injuries were reported.

The East Chicago Fire Department says between five and 10 cars needed to be uprighted following the accident. The cause of the derailment remains under investigation.