An Amtrak from Washington to New York derailed in the Port Richmond neighborhood of Philadelphia about 9:30 p.m. Tuesday.
The crash tore cars apart, sent seven cars off the track and completely destoryed the train's locomotive.
"We have confirmed an engine and all seven cars derailed," a U.S. Department of Transportation representative said on Wednesday.
The engine and two cars were left standing upright, three cars were flipped on their sides, and one was nearly flipped over on its roof. A seventh is "leaning hard," they said.
The train was travelling on Washing to Boston route, known as the northeast corridor, the busiest passenger line in the country. At the time of the crash the train was carrying 238 passengers and five crew members.
Six people have been confirmed killed and over 150 injured.
The cause is currently under investigation.
"We do not know what happened here. We do not know why it happened," the USDOT said, through a spokesman.. There was no indication the derailment was a result of an impact with another train, he said.
So far, there's nothing to indicate the incident was an act of terrorism.
The general area of the crash is known as Frankford Junction. It was the site of one of the nation's deadliest train accidents when The Congressional Limited crashed, killing 79 people, in 1943.