At least six people were killed when an Amtrak passenger train travelling from Washington to New York derailed in Philadelphia, authorities said on Wednesday.More than 140 other people were hospitalised following Tuesday night's crash. Five of the injured are listed in critical condition.Amtrak Northeast Regional Train 188 was carrying 238 passengers and five crew members when it derailed in the Port Richmond neighbourhood just minutes after making a scheduled stop at Philadelphia's 30th Street station.The National Transportation Safety Board opened an investigation into the accident, while the FBI has ruled out terrorism.Emergency personnel on Wednesday continued to search the wreckage for additional victims.Earlier in the day, media reports said that five people were killed in the train derailment.Amtrak announced an indefinite suspension of service between Philadelphia and New York.In February this year, seven people died and 12 were hurt when a Metro-North commuter train collided with a vehicle stuck on the tracks in Valhalla, New York.