UP spokeswoman Raquel Espinoza says crews are working to clear the tracks, several miles east of Mineola , but it would likely be Saturday before the line reopens.
She says nobody was hurt Thursday afternoon in the derailment of a train made up of four locomotives and 99 cars, traveling from Kingfisher, Okla., to Westwego, La.
Espinoza says the cause of the derailment is sought, but heat will be considered. The National Weather Service says the temperature in the area reached 109 degrees.
Some hopper cars overturned, spilling grain. Espinoza didn't immediately have a damage estimate.
Mineola is 75 miles east of Dallas.
