A locomotive on an Amtrak train carrying about 330 passengers derailed when it hit a backhoe south of Philadelphia on Sunday, killing two people and injuring about 35 in what passengers described as a jolt followed by a fireball.

The accident in Chester, Pennsylvania, about 15 miles (25 km) southwest of Philadelphia, was the latest in a series involving the US passenger rail carrier and occurred a few miles south of the site of a 2015 derailment in which eight people were killed.

Amtrak Train 89 bound for Savannah, Georgia, from New York struck a vehicle on the tracks, Chester Fire Commissioner Travis Thomas said. Amtrak said the vehicle was a backhoe.

The two people killed were Amtrak employees, officials said.

Thomas said 35 people on board the train were taken to hospitals and none of the injuries were life-threatening. About half of the injured had been released from hospitals as of Sunday afternoon, the Philadelphia Inquirer reported.

"We are still gathering the facts," National Transportation Safety Board investigator Ryan Frigo told a news conference.

Frigo said there were seven crew members on board the train, adding that the locomotive engineer was hospitalized.

The NTSB has recovered the event data recorder, which may be able to tell the speed of the train at the time of the crash, as well as video recordings from the train. The material has been sent to an NTSB lab in Washington for analysis, he said.

Amtrak said it would operate its normal schedule of train service along the busy Northeast rail corridor on Monday.

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 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."

The accident took place about 20 miles (30 km) south of one of Amtrak's deadliest recent accidents, where eight people were killed and 43 hurt last May.

That train was traveling at more than twice the speed limit, but a federal investigation could not determine the cause of the crash. – Reuters