NTSB launches wide-ranging probe of Philadelphia train derailment

(Reuters) - The U.S. National Transportation Safety Board has opened a broad investigation into the cause of the train derailment north of Philadelphia that left at least six people dead, an official for the agency said on Wednesday. "We're looking at the track, the train signals, the operation of the train, the mechanical condition of the train, human performance," NTSB board member Robert Sumwalt told a news conference. "We're setting up a multidisciplinary investigation to try to understand the factors that led to this accident." Philadelphia Mayor Michael Nutter said the train's so-called black box recorder had been recovered and was being analysed. (Reporting by Timothy Ahmann)