An Amtrak train headed to New York City derailed and tipped over in Philadelphia last night, killing at least six people and injuring scores more, at least five of them critically. The cause remains unclear. "It is an absolute disastrous mess," said Mayor Michael Nutter. The train had seven cars, including the engine, and six of them overturned, reports the New York Times. More than 140 people went to hospitals to be evaluated or treated, and it remained unclear this morning whether any passengers were still trapped. Train 188, a Northeast Regional whose route originated in Washington, DC, was carrying 238 passengers and five crew. It had left Philadelphia's 30th Street Station minutes before the accident, which occurred about 9:30pm near a curve in the tracks, reports the Philadelphia Inquirer. No word yet on how fast it was going.