An Amtrak train struck a piece of construction equipment just south of Philadelphia, and partially derailed in a incident that claimed two lives and injured at least 35.
Service on the Northeast Corridor between New York and Philadelphia has been suspended.
Amtrak said Train 89 was heading from New York to Savannah, Georgia, when it struck a piece of construction equipment that was on the track in Chester, about 15 miles outside of Philadelphia.
The impact derailed the lead engine of the train. About 341 passengers and seven crew members were on board.
Two Amtrak employees died.
Amtrak said initial reports are that some passengers were being treated for injuries. Local emergency responders are on the scene and the crash is being investigated.
Federal Railroad Administration officials are at the scene.
Ari Ne'eman, a disability rights activist heading to Washington after speaking at an event in New York, said he was in the second car at the time of the crash.
"The car started shaking wildly, there was a smell of smoke, it looked like there was a small fire and then the window across from us blew out," said Mr Ne'eman.
Some of the passengers started to get off after the train stopped, but the conductor quickly stopped them. Officials started evacuating people to the rear of the train and then off and to a local church.
"It was a very frightening experience. I'm frankly very glad that I was not on the first car," where there were injuries, Mr Ne'eman said.