TUCSON, Ariz. (AP) -- Union Pacific trains are again using both sets of the railroad's tracks across southern Arizona following repairs after a derailment involving 39 railroad cars carrying empty freight containers.
The cars derailed Monday evening at Picacho (pih-KAH'-cho) Peak about 40 miles northwest of Tucson, and one set of tracks was reopened late Tuesday.
Repairs of the second set of tracks were completed Wednesday morning, and Union Pacific spokesman Mark Davis said traffic flow will return to normal by late Thursday.
Davis says cause of the derailment remains under investigation, but the National Weather Service had issued a severe thunderstorm warning in the area.
The 107-car train pulled by three engines was going from Houston to Los Angeles.