A train derailed when it smashed into construction equipment on the line south of Philadelphia on Sunday, killing two people and injuring dozens, as shaken passengers described how a fire erupted in the chaotic aftermath.

The Amtrak train, which was en route from New York to Savannah, Georgia on a busy rail corridor of the US northeast, struck a backhoe and the two dead were railroad construction workers, media reports and officials said.

The front windows of the train, which was carrying nearly 350 passengers and crew, were smashed in the incident, which took place in the town of Chester, Pennsylvania shortly before 8:00 am (1200 GMT).

Travis Thomas, fire commissioner for Chester, said that 35 people received hospital treatment for "non-life-threatening" injuries.

"People are being re-routed back to Philadelphia to be reunited with their luggage," he added.

Amtrak did not immediately provide details of the two dead.

A 15-year-old passenger told reporters how the journey was going as planned until suddenly the train stopped almost dead and the car was filled with dust.

"We were on the train and everything was going smoothly. Then the train was, like, rumbling. We got off track I guess. There was a bunch of dust. There was dust everywhere. The train conductors were running to the front," he said.

"We got off track and then were was a big explosion, then there was a fire. Then the windows burst out. Some people were cut up -- but they were just minor injuries -- and then people started running."

The boy's mother, Monica Holmes, had dropped him off a half hour before the accident and sped back to the station when he called to tell her that there had been an accident.

"He called and told me, 'Mom, someone was killed on the train. It was a construction worker.' My heart just dropped," she said.

"I'm just thanking God that he's OK, and I pray for the other families that suffered the loss. I can't imagine it."

In a statement, Amtrak said that Palmetto train 89 struck a backhoe that was on the track, derailing the lead engine.

Rescuers rushed to the scene and Amtrak launched an emergency hotline for people worried about their loved ones.


'Like a nightmare'

An Amtrak spokesman, Stephen Gardner, told reporters that officials from the National Transportation Safety Board were en route to the scene to launch an investigation.

Train services along a 30-mile (50-kilometer) stretch from Philadelphia south to Wilmington, Delaware was suspended, said Amtrak officials.

Passenger Glenn Hills, who was in the second passenger car, described how the train had appeared to plow through debris on the track before slamming into the backhoe.

"I looked outside and it looked like we were in this brown cloud. We were rolling into this storm, this sandstorm," he told CNN.

"People are yelling at that point. There was a woman screaming a prayer.

"(Then) there was tremendous impact on the first car."

"It feels like a nightmare," he added.