PHILADELPHIA -- Rescue crews searched the mangled wreckage for victims Wednesday as investigators tried to determine why an Amtrak train jumped the tracks in a crash that killed at least seven people, injured more than 200 and plunged screaming passengers into darkness and chaos.
A body was pulled from the wreckage of the train Wednesday, increasing the death toll to seven. Philadelphia Fire Department Executive Chief Clifford Gilliam said the body was found as crews combed through the mangled train.
Investigators recovered the train's data recorders and said they expected them to yield crucial information, including how fast the train was going as it rounded a sharp curve and derailed in the city's working-class Port Richmond section shortly after 9 p.m. Tuesday.
"It's a devastating scene. There are many first responders out there. They are working. They are examining the equipment, seeing if there are any more people in the rail cars," Robert Sumwalt of the National Transportation Safety Board said.
A member of the Naval Academy was among the dead. Justin Zemser was on leave and on the way home to Rockaway Beach, New York when the train derailed, CBS Baltimore reported.
Award-winning AP video software architect Jim Gaines was also among those killed. Gaines, a 48-year-old father of two who joined the news agency in 1998, had attended meetings in Washington and was returning home to Plainsboro, New Jersey.
The engineer, who has not been identified, declined to provide a statement to authorities and left a meeting with an attorney, Philadelphia police said.
Amtrak inspected the stretch of track on Tuesday, just hours before the accident, and found no defects, according to the Federal Railroad Administration.
A law enforcement official told CBS News that so far there is no evidence of sabotage on the tracks at the train derailment site, and no evidence of any criminal or terrorist act.
Former NTSB Chair Deborah Hersman told "CBS This Morning" that investigators will be looking at "the human, the machine and the environment."
"They're going to be really focused on that operator," Hersman said. "What he was doing, the conditions of the cars and the track and anything unusual that might have been going on right at that point in time."
Mayor Michael Nutter said some people remained unaccounted for, raising fears the death toll could rise, though he cautioned that some passengers listed on the Amtrak manifest might not have boarded the train, while others might not have checked in with authorities.
"We are heartbroken by what has happened here," he said.
President Barack Obama said the derailment "is a tragedy that touches us all." In a statement, Mr. Obama said he and the first lady were "shocked and deeply saddened" to hear of the derailment.
Train 188, a Northeast Regional, was en route from Washington to New York when it lurched to the right and fell off the tracks at a notorious curve not far from the scene of one of the nation's deadliest train wrecks more than 70 years ago.
The conductor survived and was expected to give a statement to police. The train also had a video camera in its front end that could yield clues to what happened, Sumwalt said.
Passengers scrambled through the windows of toppled cars to escape. One of the seven cars was severely mangled. Hospitals treated more than 200 people for injuries that included burns and broken bones.
The accident closed the nation's busiest rail corridor between New York and Washington as federal investigators arrived to begin examining the twisted wreckage, the tracks and the signals.
CBS Philly spoke with a mother who was on board the train with her son.
"We were just on the train and all of a sudden it started to shake," said Joan Helfman. "And we were in the front seat and this huge red suitcase just came flying at me."
"Our train was actually on its side so it pushed me on to the side of the train. It hit my chest. I think I have a few fractured ribs. I'm a nurse."
When asked what was going through her mind, Helfman said, "That this is a nightmare and it can't be happening."
"I saw so many head injuries and bloody faces," she said. "There was nothing I could do to help, except talk to the people."
Passenger Jillian Jorgensen, 27, was seated in the quiet car - the second passenger car - and said the train was going "fast enough for me to be worried" when it began to lurch to the right.
The train derailed, the lights went out and Jorgensen was thrown from her seat. She said she "flew across the train" and landed under some seats that had apparently broken loose from the floor.
Jorgensen, a reporter for The New York Observer who lives in Jersey City, New Jersey, said she wriggled free as fellow passengers screamed. She saw one man lying still, his face covered in blood, and a woman with a broken leg.
She climbed out an emergency exit window, and a firefighter helped her down a ladder to safety.
"It was terrifying and awful, and as it was happening it just did not feel like the kind of thing you could walk away from, so I feel very lucky," Jorgensen said in an email to The Associated Press. "The scene in the car I was in was total disarray, and people were clearly in a great deal of pain."
Early Wednesday, authorities on the scene seemed to be girding for a long haul. Several portable toilets were delivered for investigators and recovery workers. Heavy equipment was brought in, and Amtrak workers in hard hats walked around the wreck.
All seven train cars, including the engine, were in "various stages of disarray," Nutter said. He said there were cars that were "completely overturned, on their side, ripped apart."
An AP Press manager, Paul Cheung, was on the train and said he was watching a video on his laptop when "the train started to decelerate, like someone had slammed the brake."
"Then suddenly you could see everything starting to shake," he said. "You could see people's stuff flying over me."
Cheung said another passenger urged him to escape from the back of his car, which he did. He said he saw passengers trying to get out through the windows of cars tipped on their sides.
"The front of the train is really mangled," he said. "It's a complete wreck. The whole thing is like a pile of metal."
Gaby Rudy, an 18-year-old from Livingston, New Jersey, was headed home from George Washington University. She said she was nearly asleep when she suddenly felt the train "fall off the track."
The next few minutes were filled with broken glass and smoke, said Rudy, who suffered minor injuries. "They told us we had to run away from the train in case another train came," she said.
Another passenger, Daniel Wetrin, was among more than a dozen people taken to a nearby elementary school.
"I think the fact that I walked off kind of made it even more surreal because a lot of people didn't walk off," he said. "I walked off as if, like, I was in a movie. There were people standing around, people with bloody faces. There were people, chairs, tables mangled about in the compartment ... power cables all buckled down as you stepped off the train."
Several people, including one man complaining of neck pain, were rolled away on stretchers. Others wobbled as they walked away or were put on buses. An elderly woman was given oxygen.
The Port Richmond neighborhood is a mix of warehouses, industrial buildings and homes.
The area where the wreck happened is known as Frankford Junction. It is not far from the site of the 1943 derailment of the Congressional Limited, from Washington to New York, which killed 79 people.
Amtrak's busy Northeast Corridor between Washington and Boston serves 11.6 million passengers a year.
The mayor, citing the mangled train tracks and downed wires, said: "There's no circumstance under which there would be any Amtrak service this week through Philadelphia."
Former U.S. Rep. Patrick Murphy was on the train and said he helped people. He tweeted photos of firefighters helping other people in the wreckage.
"Pray for those injured," he said.
Frankford Junction, the scene of the derailment, was the site of another deadly train wreck 71 years ago.