Two Union Pacific employees were killed and three people were injured when a freight train collided with a tractor-trailer and derailed in a small West Texas city, authorities said Thursday.

The train derailed around 5 p.m. Wednesday in Pecos after the collision at a railway crossing, authorities said. Union Pacific, based in Omaha, Nebraska, said Thursday that two employees had been killed.

Pecos Police Chief Lisa Tarango said the other injuries were minor.

Although hazardous materials were being carried aboard the train, none were released in the derailment, city officials said.

The hazardous materials included lithium ion batteries and air bags.

Leaked diesel fuel was contained, officials said.

The National Transportation Safety Board sent a team to investigate. It said in a statement Thursday that it doesn’t determine or speculate about the cause during the on-scene phase of the investigation.

— The Associated Press