An Amtrak train locomotive partly derailed when it hit a backhoe south of Philadelphia on Sunday, killing two people and injuring 35 in what passengers described as a jolt followed by a fireball.
The accident in Chester, about 15 miles (24 km) southwest of Philadelphia, was the latest in a series involving the US passenger rail carrier and occurred a few miles (km) south of the site of a 2015 derailment that claimed eight lives.
Amtrak Train 89 bound for Savannah, Georgia, from New York with 341 passengers and seven crew aboard struck a vehicle on the tracks, Chester Fire Commissioner Travis Thomas said. Amtrak said the vehicle was a backhoe.
"We had two deceased, but they were not passengers on the train," he told a news conference.
He gave no details about those killed. Thomas said 35 people were taken to hospitals and none of the injuries were life-threatening.
Philadelphia NBC television affiliate WCAU quoted investigators as saying those killed were Amtrak workers with more than 40 years of service between them.
Television images showed the lead engine with its front end partially off the rails and its windshields smashed.
Kim Goldman, of Washington, who was among hundreds of passengers taken to a nearby church, said she felt a bump, followed by skidding similar to airplane turbulence that lasted five to 10 seconds.
"We knew we hit something. We were just holding on, hoping we would stop," said Goldman, who was in the second car. Crew members told passengers to move to the back of the train.
Passenger Terri Dixon, of Washington, said: "There was a big bump, and a fireball. Everything happened so fast."
Amtrak suspended service between Philadelphia and Wilmington, Delaware. A broader suspension of service between New York and Philadelphia was lifted.
Amtrak said investigators from the National Transportation Safety Board were en route.
The accident took place about 20 miles (30 km) south of one of Amtrak's deadliest recent accidents. Eight people were killed and 43 hurt last May when a New York-bound train derailed in north Philadelphia.
That train was travelling at more than twice the speed limit, but a federal investigation determined that the cause of the crash remained unexplained.
Last month, about three dozen people were injured when an Amtrak passenger train derailed in Kansas.