A freight train derailed in Pittsburgh and emergency crews were called, but there were no injuries and no hazardous materials involved, a railway spokesman said. Investigators were still trying to determine how the Allegheny Valley Railroad train went off the tracks on Thursday morning, a spokesman for Carload Express, which owns the railroad, told Reuters. About 10 train cars derailed when the train was negotiating a curve in the tracks, local media reported. Pittsburgh is on the opposite end of Pennsylvania from Philadelphia, where an Amtrak train derailed, resulting in seven deaths and scores of injuries.