At least six people were killed and 50 or more were injured Tuesday night when an Amtrak train that originated in Washington derailed in Philadelphia.

Philadelphia mayor Michael Nutter told a late-night news conference that five people had died and that six of the injured were in critical condition. A sixth death was announced Wednesday morning and the number of critical was raised to eight. Police chief Charles Ramsey said officers used “a large number of tourniquets” on the injured.

“It’s an absolute disastrous mess,” Nutter said. “I’ve never seen anything so devastating.”

According to the mayor’s count, about 150 people “self-evacuated” from the train, which Amtrak officials said carried about 240 people, including five crew members.

The derailment, which occurred about 9:30 p.m., appeared to be the worst railroad accident in the busy Northeast Corridor in many years. No cause was known immediately.

Nutter said officials did not know what happened or why, and he declined to speculate.

Federal investigators were sent to the scene, in a Philadelphia neighborhood northeast of the 30th Street Station.

Rail service between New York and Philadelphia was halted.

Amtrak said early Wednesday morning that modified Amtrak service will be provided between Washington and Philadelphia, Harrisburg and Philadelphia, and New York and Boston. There will be no Amtrak service between New York and Philadelphia, but New Jersey Transit will honor Amtrak tickets between New York City and Trenton, Amtrak said.

After the derailment, Nutter said, seven cars, including the engine, were “in disarray.” They were “overturned, on their sides … ripped apart,” he said. They were in “horrible shape,” Nutter said at the news conference. Some media reports indicated that additional cars also derailed.

Some of the injured were freed after first responders cut them out of the wreckage, authorities said. About 200 police and 120 fire personnel were on the scene, Nutter said.

He also emphasized that available information was “very preliminary.”

Witnesses said the crash apparently occurred on a curving section of track. The tracks make a 45 degree turn in the vicinity of the crash site, which is about seven or eight miles from the 30th Street Station.

Andrew Cheng and his wife, in the U.S. from Singapore for a family reunion were on board along with more than a dozen relatives split up among the rail cars returning from a one day visit to Washington.

Partway through their trip to New York,  Cheng, 64, said he heard a series of bangs and felt the train slip off the tracks. “It was so quick. But you can feel that the train was derailed. It jumped. And then it kept bumping, and kept on sliding,” he said. He said he was sitting in the second-to-last car, which ended up slanted but not fully on its side when it hit the ground. He fell onto his wife, and other people, screaming, fell onto him.

He said he didn’t know what had happened for about 30 seconds. “We all — like me — black out. We don’t know what happened,” he said. Then came a rush of thoughts: “All kind of things. Family members. Am I going to die?”
Someone started shouting that the car might fully tip over if they all moved toward the lower end. So one by one, passengers started climbing out the only open window, Cheng said. Then someone — possibly someone outside the train — opened a door at the end of the car and the remaining passengers rushed out.

Cheng said he and his family members were transported to different hospitals, but he has managed to talk to all of them. He said he only knew the conditions of some of them. His sister-in-law was struck in the arm by an object and had the injury bandaged and put in a sling; his brother-in-law was in the hospital after getting slammed to the ground and pounded by someone falling on top of him; Cheng himself was examined for a stiff neck.

He and two of his relatives had just been released from the hospital shortly before 3 a.m. on Wednesday. They were transported to John Webster Little House School, not far from the crash site, which the Red Cross was using as a safe space for victims and for people awaiting news of loved ones. One man in the parking lot of the school said he was waiting for news of a friend, who had not been located.

Cheng said he had been told a bus would eventually take his family, after all 14 members are reunited, on to New York.

An employee of the Associated Press who was on the train reported that the train appeared to be slowing down. Then he felt a shaking. Peoples’ belongings hurtled over his head, he said.

Former U.S. Rep. Patrick Murphy (D-Pa.,) an anchor on MSNBC’s “Taking the Hill,” was in the train’s cafe car near the front of the line when it crashed. He told The Washington Post that the train had just stopped in Wilmington, Del., where some passengers, including Sen. Tom Carper (D-Del.), had departed. Shortly after, the car started to rock — first to the left; then to the right.

He said he slammed into a window. Then he knocked into a fellow passenger.

“I landed on someone who had taken Sen. Tom Carper’s seat,” he told The Post in an interview. “It was pretty dark and extremely dusty with debris flying all over. People screaming. People crying. I pulled myself up, reached over to the window and punched out the emergency window with my palm and tried to help people get out.”

Murphy soon sent out a message on Twitter, saying, “I’m ok. Helping others. Pray for those injured.” Then he posted a photo showing first responders climbing inside a train car, which appeared to be leaning over. Another image showed wounded passengers on board.

It was not clear how many of those who boarded the train in Washington remained on board as it left the Philadelphia terminal.

A Philadelphia news site reported that Carper had left the train in Wilmington.

There were multiple reports on Twitter feeds that there was smoke in at least one of the cars. One of the messages said that passengers who were able to move were trying to get the door open so they could climb down from the car, which was apparently on its side.

Another tweet came from someone who reported being in a car tilted at a 45-degree angle.

In media interviews passengers told of a chaotic scene inside the railcars, with luggage flying around, and disheveled victims bleeding and crying.

Video footage from the scene showed cars under the illumination of floodlights as the flashlights of rescue workers swept across the silver sides of several of them.

The Philadelphia Police Department asked residents to stay away from the scene so first responders could operate more efficiently.

A published timetable said the train was scheduled to leave Washington’s Union Station at 7:10 p.m. and arrive in Philadelphia about two hours later.

The Federal Railroad Administration was sending a team of investigators to the site. The National Transportation Safety Board was also to investigate.