An Amtrak train outside Philadelphia derailed with over 340 on board Sunday morning.
Two passengers were confirmed dead and 35 people were reported injured.
None of the injuries were considered life-threatening, officials told reporters at a Sunday news conference where NTSB investigator Ryan Frigo said the train's engineer was among those taken to the hospital.
The train, en route to Savannah, Georgia from New York City, hit a construction vehicle that was on the tracks, according to an Amtrak statement. Frigo said he did not know why the equipment was on a track.
An official confirmed that one of the victim's was the equipment operator. Sen. Chuck Schumer said he was told the other person killed was a supervisor. Both victims were reportedly Amtrak employees.
The derailment occurred just before 8 a.m. near Chester, Pennsylvania. Passengers reported seeing a lot of debris on the tracks leading up to the crash.
"This morning, Amtrak Train 89, operating from New York City to Savannah, Ga., struck a backhoe that was on the tracks" Amtrak said in a statement on Sunday.
Amtrak said the derailment affected the train's lead engine.
There were approximately 341 passengers and seven crew members on board.
One of the passengers was businessman and former presidential candidate Steve Forbes, who told Book Tv he was in the next to last car during the crash.
Forbes said the train first "made sudden jerks" before coming to an abrupt stop. "Everyone's coffee was flying through the air."
"The most disconcerting thing ... (was) not knowing what had happened," Forbes said.
Sen. Schumer, meanwhile, seemed confident the tragedy could have been prevented.
"Clearly this seems very likely to be human error," Schumer said. "There is virtually no excuse for a backhoe to be on an active track."
The investigation into the cause of the crash remained ongoing Monday morning.