In an instant, an uneventful commute Thursday morning turned to chaos when NJ Transit train No. 1694 slammed into concrete and steel at the Hoboken Terminal.

The lights went out and it became dark inside the first car where Mike Scelzo was a passenger.

Debris tumbled down around him and other passengers, said Scelzo, 49, of Oradell, New Jersey.

What he saw and heard next was “just a haze of smoke” and the terrifying sounds of crying and screaming commuters.

“We were riding along,” said Scelzo, on his way to work at Amazon.com in Jersey City, New Jersey. “I was talking with the person that I rode in with and all of a sudden everything just stopped — really hard.”

Inside the terminal, passengers and bystanders ran for cover amid the crush of cascading steel and debris. Some made it to safety unscathed. Others had no such luck.

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The train had plowed into a terminal platform teeming with commuters waiting to board. It stopped just short of the wall that separates the tracks from the terminal’s interior.

The terminal’s canopy roof and beams collapsed, leaving behind twisted metal.

A woman on a platform was killed after debris landed on her.

At least 114 passengers and bystanders were injured. Some were in critical condition. Others received cuts and bruises.

On board Scelzo’s mangled car, passengers — stunned and shaken — pulled down an emergency window, climbed out and jumped onto the platform, he said.

Nassima Toumi, a personal trainer, was getting coffee inside the terminal when she heard the crash.

She immediately thought of her husband who was waiting in another part of the terminal to board NJ Transit light rail.

Toumi said she rushed to search for him and, like other witnesses, saw passengers and bystanders — some clad in blood-soaked clothes — being treated by rescuers.

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“There were bodies everywhere by the time I walked there,” Toumi said. “There were people covered in blood. One woman was on the ground and her whole leg was opened, bleeding.”

When Toumi found her husband, he was in tears.

People who were thrown off their feet by the force of the crash, slowly got up — some with help — and staggered away, according to other witnesses.

William Blaine, a transit employee, was in the Dunkin’ Donuts shop when he heard the crash.

“The whole place shook, like an earthquake,” he said.

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Tom Spina also inside the terminal, said he heard a loud boom and the lights kind of flickered.

At first, Spina had no idea what could have caused such a concussion.

“I ran out and that’s when I realized it was the train,” he said.

The train left Spring Valley, New York, at 7:23 a.m., and commuters said the ride was ordinary before the crash.

“This was confusing because there were no problems during the rest of the commute,” said Omar Maamoun, 18, a student at Stevens Institute of Technology, who was in one of the rear cars.