(FAIRFIELD, Conn.) -- Federal transportation officials began their investigation Saturday to determine what caused two commuter trains to crash head-on in Connecticut during the Friday rush hour.
At least 70 people were injured Friday when a Metro-North train derailed and barreled straight into the path of another train headed in its direction just outside Bridgeport, Conn.
Investigators from the National Transportation Safety Board arrived at the scene Saturday morning to begin surveying the twisted rail cars that remained on the tracks.
"We'll be looking at how the crew behaved and how the crew operated the train," NTSB member Earl Weener said.
During the investigation, which is expected to last seven to 10 days, officials will also examine the braking performance of the trains and the conditions of the wheels, cars and track to see if they played a role in the crash, Weener said.
Gov. Dannel Malloy said three people remained in critical condition on Saturday, while six others also remained hospitalized for their injuries. Many of the injured suffered bruises, cuts and minor fractures and were able to be treated and released, according to officials at two area hospitals.
A Metro-North train was traveling east from New York City's Grand Central Station to New Haven, Conn., when it derailed at 6:10 p.m., Weener said.
The jolt of the impact was so strong, passengers said it caused bodies to be flung around the cars.
Sen. Richard Blumenthal, D-Conn., was among the elected officials who surveyed the damage and called the scene "absolutely staggering."
He said the injuries could have been much worse and lauded the investment in infrastructure for saving lives.
"Investment in quality of transportation is probably one of the lessons we will learn from this accident," he said.
While the wreckage remains on the tracks, transportation in the Northeast Corridor is expected to be crippled.
Two of the tracks on the line were already out of service for a project, and the remaining two tracks were damaged in the collision, according to the Metropolitan Transportation Authority, which operates the Metro-North Railroad.
Amtrak's service between New York City and Boston, which operates on the tracks where the accident occurred, was also suspended indefinitely.
Commuting could be a challenge on Monday for those around Bridgeport who rely on Metro-North to get to and from work in New York City.
Malloy said a system was being set up to move people from Bridgeport to nearby train stations.
"This is going to be with us for a number of days," he said.
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