Two railroad workers were killed Sunday and more than 30 people injured when an Amtrak train from New York to Savannah, Georgia, derailed just outside Philadelphia, officials said.

Amtrak’s Northeast Corridor service between New York and Philadelphia was suspended for part of the day, officials said, after Amtrak Train 89 hit a backhoe in Chester, Pennsylvania.

Amtrak service would resume completely on Monday although there may be some delays on Acela Express, Northeast Regional and other services between Philadelphia and Wilmington, Delaware, company officials said Sunday night.

Ryan Frigo, an investigator with the National Transportation Safety Board, said at a Sunday night news conference that the event data recorder and forward-facing and inward-facing video from the locomotive had been recovered. He said the locomotive engineer was among those taken to hospitals. Officials said earlier that none of the injuries was deemed life-threatening.

Earlier Sunday, Sen. Chuck Schumer (D-N.Y.) told reporters at a Manhattan news conference on another matter that Amtrak board chairman Anthony Coscia informed him the workers killed were both Amtrak employees: a backhoe operator and a supervisor. He said debris from the crash flew into the first two cars, causing the injuries to passengers.

Amtrak spokesman Michael Tolbert said about 340 passengers and seven crew members were aboard the train.

The Delaware County medical examiner’s office said no information would be released until after autopsies Monday.

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Frigo said he did not know why the equipment was on a track the train was using. He said scheduling, the track structure and the work that was being performed at the time of the accident would be part of the investigation. The event data recorder has been sent to the NTSB’s laboratory in Washington and will answer such questions as how fast the train was going at the time of the crash, he said.

Schumer said it was unclear whether the backhoe was performing regular maintenance, which is usually scheduled on Sunday mornings because there are fewer trains on the tracks, or whether it was clearing debris from high winds in the area overnight. But he said Amtrak has “a 20-step protocol” for having backhoes on the track, and no trains are supposed to go on a track where such equipment is present.

“Clearly this seems very likely to be human error,” Schumer said, calling for Amtrak to review its processes. “There is virtually no excuse for a backhoe to be on an active track.”

The train struck the backhoe on the track in Chester, about 15 miles from Philadelphia, and the impact derailed the train engine, according to Amtrak officials.

Along with the NTSB, officials with the Federal Railroad Administration were also sent to the scene, said Matthew Lehner, a spokesman for the agency.

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The derailment comes less than a year after an Amtrak train originating from Washington, D.C., bound for New York City derailed in Frankford Junction, Pennsylvania, near Philadelphia. Eight people were killed and more than 200 were injured in that May 12 crash.

Passengers with travel plans can change their itinerary or review refund information on Amtrak.com or call 800-USA-RAIL. Service alerts, passenger notices and other announcements are also posted at Amtrak.com/alerts.

With Matthew Chayes and The Associated Press