The accident was reported shortly after 4:30 a.m. "The wreckage was mangled up," said Sr. Trooper Chris Ray. "It sounded like thunder," truck driver Sandy Strickland, who was nearby when the accident happened, told the Amarillo Globe-News. Joe Faust, a spokesman for Fort Worth-based BNSF, said no hazardous material spilled and that the trains were hauling flatbed cars carrying truck trailers. The National Transportation Safety Board was sending a team of investigators to the scene. Two workers on the first train suffered injuries not believed to be life-threatening. Two crewmembers on the second train were critically injured and transported to an Amarillo hospital, Faust said. Names of the workers and details of their injuries were not immediately released. Preliminary estimates indicate between 20 and 30 cars derailed, Faust said. KFDA-TV reported that at least one locomotive ended up on its side. Rail traffic was being rerouted and there was no immediate timetable for clearing the tracks, Faust said. No nearby residents were in danger due to the accident. Copyright 2013 The Associated Press.