More than 40 people were injured on Tuesday after a high-speed train made contact with an unoccupied parked train outside Philadelphia, according to official with the Southeastern Pennsylvania Transportation Authority.
The collision happened just after midnight at a transportation terminal in Upper Darby, about 30 minutes west of Philadelphia, a SEPTA spokeswoman said.
Forty-two people, including the train's operator, sustained non-life-threatening injuries, she said.
The spokeswoman did not specify how the trains made contact but said the collision involved two trains, including an inbound train on SEPTA's Norristown High Speed line.
The collision is under investigation, and police, medics and safety operations workers are on scene, SEPTA officials said.
In an early morning briefing, Upper Darby Mayor Nicholas Micozzie said victims were taken to area hospitals and that four people suffered serious injuries, according to The Associated Press.
One witness, who said he was on the train at the time of the collision, said it occurred just as he stood up to get off the train.
"My face hit the wall, put a big hole in the wall, and I went straight down. I blacked out," the witness said in an interview with KYW-CBS on Tuesday. "There was blood everywhere. The driver was all banged up, and there was this one girl bleeding out of her face pretty bad."
ABC News' Rachel Katz contributed to this report.