Karl Baker and Brittany Horn, The (Wilmington) News Journal and John Bacon, USA TODAY

CHESTER, Pa. — Two Amtrak workers were killed and dozens of passengers were injured when a train bound for Washington, D.C., slammed into a backhoe south of Philadelphia on Sunday morning, authorities said.

The tragedy, which halted service along much of the Northeast corridor, came less than one year after an Amtrak derailment in Philadelphia killed eight people.

Amtrak Vice President Stephen Gardner said the lead engine of the Palmetto train, which runs from New York City to Savannah, Ga., derailed at about 8 a.m. ET with 341 passengers and a crew of seven. Chester Fire Commissioner Travis Thomas said two people were killed.

Sen. Chuck Schumer, D-N.Y., said he was told by Amtrak board chairman Anthony Coscia that the backhoe operator and a supervisor, both Amtrak employees, were killed, the Associated Press reported.

Schumer, speaking in New York, said it’s unclear whether the backhoe was performing regular maintenance or was clearing debris from high winds overnight.

Gardner said 31 passengers were taken to hospitals with non-life-threatening injuries. Other passengers were being transported by bus to train stations in Philadelphia and Wilmington, Del.

"Local emergency responders are on the scene and an investigation is ongoing. Northeast Corridor service between New York and Philadelphia is suspended," Amtrak said in a statement. Amtrak later announced that service between Wilmington and Philadelphia was suspended but was expected to resume within hours.

Federal Railroad Administration spokesman Matthew Lehner said federal investigators were on the scene, and the National Transportation Safety Board sent a team.

NTSB investigator Ryan Frigo said the train's event data was sent to Washington for analysis. Information from the device will help investigators determine the train's speed during the collision, he said.

Frigo could not answer why workers were on the track Sunday morning, whether the train's engineer was alerted about them or whether a warning system exists.

“This is something we look at as part of our investigation but I do not have that factual information,” Frigo said.

Donovan Bryan, a Defense Department worker from Springfield, Va., said he was in the third car from the front when the train, rolling "full bore" at 50 or 60 mph, hit the construction equipment.

"I heard the bang and saw the flames shoot up, and then the train eventually came to a halt after maybe around a minute or so," he said while waiting for his wife to pick him up at a staging area set up at a local church.

"You could feel the hit, and then (the train car) jumped and I saw flames,” he said. “And I felt the heat from the flames.”

Also on the train was former Republican presidential candidate Steve Forbes, who tweeted Sunday, "Prayers to families of those killed and injured."

Mariam Akhtar, of Washington, D.C., told 6abc.com that she was on the sixth car of the train.

"It felt like the train hit something and there were like three or four really big bangs and it kind of threw us off the seats we were sitting in," she said. "There was a lot of smoke and everybody was yelling."

Ari Ne’eman, a disability rights activist from Silver Spring, Md., who was traveling from New York to Washington, told the Associated Press she was in the train's second car. She said the conductor sent people to the rear of the train, where they were evacuated to a nearby church.

“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,” Ne’eman told AP. “It was a very frightening experience. ... I was just so thankful that the train had come to a stop and we were OK.”

The collision caused delays across the Northeast corridor. Passengers found themselves stuck with few answers as to what was happening and the reason behind the delays.

Susan Buckley, who was on her way home to New York, boarded a train early Sunday morning in Washington, D.C., and had no problems until she hit Wilmington. There, an unusually long stop prompted questions from riders, who were told there was a hold ahead on the tracks and they would have to wait.

"Finally they came on and told us there was a derailed train and we were stuck for hours and we should find other means of transportation," Buckley said. "Our favorite announcement was, 'Hello folks, just giving you an update. ... There's no update. The train is stopped indefinitely.'"

The cause of the crash was not immediately known. On May 12, 2015, a northbound Amtrak train barreled into a curve in Philadelphia at 106 mph, causing a derailment that killed eight people and injured 200. The NTSB is expected to issue a final report on that crash by summer.