Flower Mound police have shut down southbound U.S. Highway 377 from Cross Timbers Road into Roanoke.
"At approximately 6:00 p.m., the Roanoke Police Department received multiple 911 calls about a Union Pacific train derailment", the Roanoke Texas Police said in a statement.
The railroad runs parallel to the two-lane highway. Northbound traffic remained open.
Emergency crews have blocked off the southbound lane of US 377 in the Roanoke/Flower Mound area, after approximately twenty train cars derailed and plummeted from a bridge. The cause of the crash had not been determined, though the bridge over Denton Creek "appears to have failed", Pettigrew said.
"The train was not carrying any hazardous materials", Pettigrew said.