The 5:54 from Poughkeepsie was rumbling through the Bronx on Sunday morning. Only 100 to 150 people were onboard — department store employees who were bracing for another busy after-Thanksgiving day, tourists from Texas who wanted to climb the Statue of Liberty, a police officer moonlighting as a security guard on his day off.

Some were dozing when the train rounded a bend near where tracks pass under the Henry Hudson Bridge. Some were listening to music on headphones. Suddenly, with a jerk that disrupted the steady train’s steady rhythm, their world turned upside down as they were hurled from one side to the other.

In the chaos of screeching metal and the shower of debris as the train kept plowing along, some passengers grabbed for the luggage racks and held on. Others hugged their seats as the eight cars of the train flew off the tracks and several landed on their sides.

“I’m thinking I’m going into the water,” said Eddie Russell, 48, who had been listening with his eyes closed to LL Cool J. “I was thinking of me, surviving.”