A broken rail on the track may have caused Sunday's 12-car train derailment, according to a preliminary Union Pacific Railroad investigation.
The tank cars filled with crude oil derailed about 11:30 a.m. Sunday near the Texarkana, Texas, viaduct.
No one was injured, and no crude oil leaked or spilled from the train, said Jeff DeGraff with Union Pacific's Media Relations Department.
DeGraff said Monday the investigation is not complete but preliminary reports indicate that a broken rain inside the rail yard caused the derailment.
He said cleanup of the incident was completed Monday afternoon.