- One of the victims was a student at the U.S. Naval Academy, a source says
- National Transportation Safety Board officials arrive at the accident scene to begin an investigation
- The train was carrying 238 passengers and five crew members
Philadelphia (CNN)Latest developments:
• National Transportation Safety Board officials are at the accident scene.
• A sixth person has died as a result of the Amtrak train crash in Philadelphia, a doctor at Temple University Hospital said Wednesday morning.
• One of the six killed was a student at the U.S. Naval Academy, a source says.
As day broke in Philadelphia on Wednesday, rescue workers were still searching inside the mangled wreckage of an Amtrak train that derailed the night before, killing at least six people and sending another 150 to various hospitals.
Among those killed was a midshipman from the U.S. Naval academy in Annapolis, Maryland, a source close to the Naval Academy said.
Temple University Hospital medical director Herb Cushing said Wednesday morning that 25 passengers were still at Temple -- the closest trauma center to the crash site -- eight of them in critical condition.
Cushing said many of the injuries suffered by passengers came when other passengers or objects fell on them.
"It is an absolute, disastrous mess," Philadelphia Mayor Michael Nutter said of the crash site. "I've never seen anything like this in my life."
Amtrak Northeast Regional Train 188 was traveling from Washington to New York carrying 238 passengers and five crew members when it derailed about 9:30 p.m. Tuesday in the Port Richmond neighborhood of Philadelphia.
The impact tore cars apart, sending seven of them flying from the tracks, and left the engine a mangled mess.
"We have confirmed an engine and all seven cars derailed," a U.S. Department of Transportation representative told CNN on Wednesday, adding that the engine and two cars were left standing upright, three cars were tipped on their sides, and one was nearly flipped over on its roof. The seventh one is "leaning hard," they said.
"We do not know what happened here. We do not know why it happened," Nutter said. There was no indication the derailment was a result of an impact with another train, he said.
Officials with the National Transportation Safety Board arrived at the scene Wednesday morning to begin the investigation into what happened.
So far, there's nothing to indicate the incident was an act of terrorism.
The moment of impact
"Until the second of impact, everything was normal," passenger Daniel Wetrin told CNN. "Then it was just chaos."
Jeremy Wladis was in the very last car, eating.
"The next thing you know, the train starts doing funny things, and it gradually starts getting worse and worse," he said.
Then, things started flying -- phones, laptops. "Then people."
"There were two people in the luggage rack above my head. Two women, catapulted (there)."
Firefighters arrived to find seven cars and the train's engine derailed. Most of the passengers were able to escape, climbing out of windows to safety. Crews had to cut through the cars to get to others.
'Please make it stop'
Janna D'Ambrisi was in the second-to-last car, reading a book when she felt the jolt.
"Suddenly it felt like we were going a little too fast around a curve," she said.
The car she was in started to tip, and she was thrown onto another girl.
"People started to fall on us," D'Ambrisi said.
"I just held on to her leg and sort of bowed my head and I was kind of praying, 'Please make it stop.' "
Fortunately, her car didn't tip over and she was able to make it out safely.
'Heavily used stretch of track'
The Northeast Corridor, which reaches from Washington to Boston, is the busiest passenger line in the country.
The area of the crash in Philadelphia, known as Frankford Junction, was the site of one of the nation's deadliest train accidents; the Congressional Limited crash of 1943 killed 79 people.
"It's an extremely heavily used stretch of track," transportation analyst Matthew L. Wald said of the area. "They have trouble keeping it in a state of good repair."
The derailment was Amtrak's ninth this year alone, according to the Federal Railroad Administration, and while its cause has not yet been determined, some, like Wald, are already discussing the nation's aging rail infrastructure.
"The President has been a longtime advocate for investing in our infrastructure and making sure that we have the kind of 21st century infrastructure we know is going be critical to the success of our country," White House press secretary Josh Earnest said on CNN's "New Day." Earnest said that the Obama administration is "hard at work" trying to figure out what caused the crash, and that their thoughts and prayers are with the families of everyone effected.
Service between Philadelphia and New York City remained suspended Wednesday, according to Amtrak. Those seeking information about friends and family aboard the train can call an Amtrak hotline established for this incident: 1-800-523-9101.