Two commuter trains serving the US city of New York have collided in Connecticut state during evening rush hour, injuring at least 49 people, authorities say.
There have been no reports of fatalities in the Friday collision.
The Metro-North Railroad, a commuter line serving the northern suburbs, said a "major derailment" had occurred near Fairfield, just outside the town of Bridgeport.
It said emergency workers were at the scene of the accident, which occured shortly after 6:00pm local time (2200 GMT) on Friday.
Bill Kaempffer, a spokesman for Bridgeport public safety, told The Associated Press that about 49 people were injured, including four with serious injuries.
About 250 people were on board the two trains, he said.
Photos taken at the scene showed a train car askew on the rails, with one end smashed and brushing against another train. Amtrak suspended service indefinitely between New York and Boston.
"At this stage, we don't know if this is a mechanical failure, an accident or something deliberate," Lt James Perez, a spokesperson for Fairfield police, told the Connecticut Post.
The railroad said 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.
Bridgeport Police Chief Joseph Gaudett said everybody who needed treatment had been attended to, and authorities were beginning to turn their attention to investigating the cause.