No fatalities were reported following Friday evening’s collision near Fairfield on the Metro-North Railroad.
The rail line referred to it in a news release as a “major derailment.”
A spokesman for public safety officials in nearby Bridgeport says about 250 people were on the two trains that collided after one derailed.
The railroad says a train that departed New York City’s Grand Central station en route to New Haven derailed. A westbound train on an adjacent track then struck the derailed train.
Some cars on the second train also derailed as a result of the collision.
Amtrak suspended service indefinitely between New York and Boston.