A fireball goes up at the site of an oil train derailment in Casselton, N.D., in this Dec. 30 photo. The fiery crash left an ominous cloud over the town and led some residents to evacuate. Bruce Crummy/AP hide caption

itoggle caption Bruce Crummy/AP

An injured man who was on a subway train that derailed Tuesday in Moscow talks on his phone after being treated by paramedics. Dmitry Serebryakov/AFP/Getty Images hide caption

itoggle caption Dmitry Serebryakov/AFP/Getty Images

A train passes by the scene of repair efforts Tuesday at the site of a train derailment in the Bronx borough of New York. Seth Wenig/AP hide caption

itoggle caption Seth Wenig/AP

Monday, as a train on an unaffected track passed by (in the background) work continued on removing the commuter cars that derailed the day before. Mark Lennihan/AP hide caption

itoggle caption Mark Lennihan/AP

Search and rescue teams work at the scene of Sunday's passenger train crash in the Bronx. The train crash killed four people and injured dozens more. Craig Ruttle/AP hide caption

itoggle caption Craig Ruttle/AP

Emergency personnel respond to the scene of a train derailment in Santiago de Compostela, Spain. Antonio Hernandez/El Correo Gallego via AP hide caption

itoggle caption Antonio Hernandez/El Correo Gallego via AP

At a school in Lac-Mégantic, Quebec, the town's people have been waiting for word about their friends and family members. Christinne Muschi /Reuters /Landov hide caption

itoggle caption Christinne Muschi /Reuters /Landov

A still image from a video posted by Eastern Truck and Trailer captures a moment just before a commercial truck's trailer was struck by a freight train Tuesday. ETT Corp/YouTube hide caption

itoggle caption ETT Corp/YouTube