Chris Christie: Deadly Amtrak derailment "disconcerting"

For New Jersey Gov. Chris Christie, the deadly derailment of an Amtrak train Tuesday night in Philadelphia hit a bit too close to home.

"As you guys know, I ride that train route often and have for the past 13 years," Christie told reporters outside a diner in Tilton, New Hampshire, where he's drumming up support for a potential presidential bid. "So it's really disconcerting, and my thoughts go out to the families of those who have been lost and been injured."

Six people were killed and dozens more were injured, including eight who remain in critical condition at nearby hospitals, when the train headed from New York City to Washington, D.C. derailed while taking a turn in Philadelphia.

Christie, whose state borders Philadelphia, said he'd asked New Jersey's emergency management team to reach out to the city's officials and see whether they needed assistance. "They told us at the time they didn't need help. They thought they had the situation under control," he said.

Disaster response teams spent the night digging through the wreckage to make sure that there were no more passengers or personnel on the train. No cause has yet been identified, but the investigation is underway.

"I'm fascinated to know what happened, since me and a lot of my staff ride that train on a regular basis," Christie said. "Hopefully we'll get to the bottom of why it happened and make sure that we try to do what we need to do to try to prevent it from happening again."

Deborah Hersman, the former chairwoman of the National Transportation Safety Board, told CBS News the investigation will be "really focused" on the operator of the train: "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."

She also said they'll be looking at the train's recorders for information "about braking, throttle positions, speed."

Former Pennsylvania Congressman Patrick Murphy, who is also an Iraq war veteran, was on the train when it derailed. "It just happened so fast. Obviously a lot of debris, lights went out, a lot of screaming," he recalled.

Murphy wasn't injured, so he began helping people around him who were. "We have an ethic in the military, you know, we leave no one behind and I wasn't going to climb out when there were people still hurting."

A lieutenant commander in the office of the Superintendent of the U.S. Naval Academy confirmed to CBS News that one of the people killed during the derailment was a member of the service academy in Annapolis, Maryland.

CBS News Hannah Chanpong-Fraser contributed to this report.