A New York-bound Amtrak train carrying 238 passengers and five crewmembers derailed in Philadelphia Tuesday night, killing six people. Officials are still sifting through wreckage and trying to determine the exact extent of the destruction.

At a press conference Wednesday morning at the site of the crash, Philadelphia Mayor Michael Nutter announced that the train's black box recorder had been recovered and was going to be analyzed. He also said that not all of the train's passengers had been accounted for yet, asking anyone with information or missing a family member to call 800-523-9101 and report it.

The cause of the derailment remains unknown as well. Train No. 188 was en route from Washington when, at about 9:30 p.m., it flew off the rails and rolled over onto its side. Many of the cars were crumpled up and twisted.

"It's an absolute disastrous mess," Mayor Nutter said. "I've never seen anything like this in my life."

The National Transportation Safety Board is also on the scene investigating. They are regularly updating their Twitter with relevant information.