No injuries were reported when an Amtrak train derailed Monday morning in the South Loop.

The Lake Shore Limited trains 49 and 449 — which began in Boston and in New York City before combining in Rensselaer, N.Y. — were an hour behind schedule coming into Union Station when the derailment happened, Amtrak spokesman Marc Magliari said.

“As the train was moving from track to track, three of the 11 cars on the train lost contact with the track” around 10:30 a.m., Magliari said. The cause of the derailment wasn’t immediately known.

The 197-passenger train was stopped immediately and passengers in the three cars that derailed were moved to the front of the train and brought into the station before noon along with the other passengers, he said.

“We will be working both internally and with the regulatory agencies to explain what happened,” Magliari said.

A passenger on the Amtrak train posted a short video.

It was the second derailment involving an Amtrak passenger train in four days. An Amtrak train derailed and sideswiped a New Jersey commuter train at New York City’s Penn Station on Friday. That incident caused only minor injuries.

Contributing: Sun-Times Wire