Sixty people were injured, five of them critically, and rail traffic from New York to Boston was shut down after a Metro-North commuter train derailed and plowed into a second train Friday in Fairfield, Conn., Gov. Dan Malloy said.

An eastbound train derailed at 6:10 p.m. ET and struck a westbound train between the Fairfield and Bridgeport stations, a Metropolitan Transportation Authority official told NBC News.

60 people were injured after two commuter trains collided in Connecticut Friday at the peak of the evening commute. Authorities say the initial investigation shows the eastbound train derailed, colliding with a westbound train. NBC's Michelle Franzen reports.

"We have no reason to think it was anything other than an accident, but that has to be explored," Malloy said.

"We came to a sudden halt. We were jerked. There was smoke," Alex Cohen, a Canadian passenger on the westbound train en route to New York, told NBC Connecticut.

"People were screaming; people were really nervous. We were pretty shaken up. They had to smash a window to get us out," he said.

NBC Connecticut: 60 injured, five critically, in Metro-North train collision

Malloy said 60 people were transported to area hospitals, most of them with only minor injuries. Five, however, were critically injured, one of them very critically, he said.

The Metro-North train that departs New York City’s Grand Central Station for New Haven, Conn., at 4:41 p.m., with an estimated 300 passengers, derailed near the I-95 overpass in Bridgeport, MTA said in a statement. The train that leaves New Haven’s State Street station for Grand Central at 5:30 p.m., carrying about 400 passengers, struck the derailed train, the statement said.

There was no immediate word on what caused the derailment or how fast either train was going. That will be determined by the National Transportation Safety Board, which will lead the investigation.

Connecticut Gov. Dan Malloy gives details on the collision of two Metro-North trains, which injured 60 people and shut down rail traffic between New York and Boston.

Amtrak services were suspended between New York and New Haven early Saturday, Amtrak said in a statement. Limited Northeast Regional services were available between Boston and New Haven, and all Amtrak services were operating normally between New York, Philadelphia and Washington, D.C., the statement said.

Metro-North, which runs between New York City and its northern suburbs in New York and Connecticut, is one of the busiest commuter rail services in the U.S. There are four tracks on that segment of the New Haven Line, MTA's statement said, but two are out of service for replacement of overhead wires.

There was "extensive damage" to the track and the wire from the collision, MTA said. The train cars will remain in place until the investigation is completed. MTA gave no estimate for the duration of the investigation or subsequent repairs.

Passengers should expect sharply curtailed service through the weekend and beyond, Malloy said. "We have a very old system on our Connecticut section. We're involved in hundreds of millions of dollars in replacement of that system.

"It will slow the recovery," he said. "Obviously, we don't have alternative tracks to go to."

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Christian Abraham / AP Emergency workers arrive at the scene of a train collision Friday, May 17, in Fairfield, Conn. Rail traffic is expected to be snarled for several days.

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