An Amtrak train locomotive partly derailed when it struck a backhoe south of Philadelphia on Sunday, killing two people and injuring 35, officials said.
Amtrak, the U.S. passenger train company, suspended service between Philadelphia and Wilmington, Delaware. It lifted a previous suspension of service between Philadelphia and New York.
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. Thomas gave no details on those killed.
Thomas said 35 people were taken to hospitals and none of the injuries were life-threatening. Passengers were being returned to Philadelphia to pick up their luggage, he said.
Fox News said those killed were construction workers who were unable to clear the tracks in time. It quoted witnesses as saying the train's horn sounded before it struck the equipment.
Passenger Stephanie Burroughs described a fireball and windows on the train being blown out upon impact.
"The conductor did inform us that there was a fatality, that there were people working on the track," she told Fox News.
Investigators from the National Transportation Safety Board were en route, said Stephen Gardner, Amtrak executive vice president.
The Trainer United Methodist Church in Chester, about 15 miles (24 km) southwest of Philadelphia, was being used as a staging area and hundreds of passengers were in the church's gymnasium, a church spokesman said.
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 traveling at more than twice the 50 mph 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.