Clean up in Hoxie continues after a deadly train collision Sunday morning that killed two railroad workers and injured two more workers. Officials with the National Transportation Safety Board continue to investigate what caused the accident while highway crews are working on cleaning up the accident site. Federal investigators tell the Associated Press they are looking at a signal to see if it gave any final instruction to a southbound train to see whether it was signaled to slow down to stop. Two Union Pacific freight trains collided head on around three Sunday morning. U-S Highway 67 is still closed to motorists, but could open as early as this weekend or the first part of next week. The first written report on the investigation into the train crash could come in the next two weeks.