A collision caused dozens of train cars to go off the tracks in Hempfield, Pennsylvania.

A Norfolk Southern mixed-freight train heading west from Altoona to Conway collided with the back of a Norfolk Southern intermodal train – which caused a massive derailment, officials confirmed.

Norfolk Southern crews are now at the scene to handle the cleanup, but it's unclear how long that will take.

According to Norfolk Southern, shipments will also be delayed significantly because of this incident.

The company said shipments heading to the following cities will be delayed at least 18-24 hours: Chicago, Kansas City, St. Louis, New York and New Jersey.

The cause of the initial collision is still under investigation.