Three railroad workers remained missing on Monday after two freight trains collided head-on and exploded into flames in the state of Oklahoma a day ago, U.S. media reported.

The two Union Pacific freight trains collided on Sunday morning near the Oklahoma town of Goodwell, on a track that links southwestern Kansas with the northern Texas Panhandle, according to FOX news.

Three of the four crew members, including two engineers and one conductor, went missing after the collision, Union Pacific Railroad spokeswoman Raquel Espinoza was quoted as saying.

The conductor of the westbound train jumped off before the crash, she added.

The eastbound train was carrying mixed freight, including a container of hazardous resin, and the westbound one was carrying vehicles, according to media reports.

Firefighters were working to cool the freight cars, and a crew was dispatched from Fort Worth, Texas to smother the flames with foam.

It was not immediately known why the two trains were traveling toward one another on the same track, authorities said.