NEW YORK (CBSNewYork) — New Jersey Gov. Chris Christie is calling for “a full investigation into all potential causes” following a derailment of a NJ TRANSIT train Thursday night in the Hudson River Tunnel.

The derailment came just days before major repair work is set to begin on Penn Station’s switches and tracks.

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“The safety of New Jersey citizens is paramount and we will do everything possible to ensure that NJ TRANSIT and Penn Station are safe,” Christie said in a statement.

Regular service resumed Friday morning in and out of Penn Station following Thursday’s incident, but NJ TRANSIT says there may still be delays up to 15 minutes in and out of New York.

The slow-speed derailment happened around 9 p.m. Thursday when the 7:20 p.m. train from Long Branch, New Jersey heading for Penn went off the track in the Hudson River tunnel with about 180 people on board.

Passengers say they first felt a big jolt.

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“All of a sudden, the car started to swing very heavily,” said passenger Sherif Ahmed. “We were told that it was a switch problem initially. People were like, ‘that’s a lie, that’s a lie.'”

No one was hurt, but those stuck were anxious to get to their destinations.

Ahmed recorded a video from inside of the train car he was in as one of the passengers was passing around a carton full of blueberries while they waited for a rescue train to reach them.

“The firefighters and the cops were so helpful,” Ahmed said. “The vibe on the train was really cooperative. People wanted to get off and that was clear, but people were really resilient and calm.”

As firefighters attended to passengers on the stuck train, at Penn Station there was a flurry of emergency responders as all NJ TRANSIT trains were suspended while they got a hold of the situation.

The stranded passengers finally pulled into Penn Station after 11 p.m. As for why the train derailed, NJ TRANSIT says it’s working with Amtrak, which runs Penn Station, to find out.

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Amtrak has also resumed regularly scheduled operations at Penn following the derailment with some minor congestion-related delays.