The train derailed on a large curved section of track at 7:20 a.m. in New York about 100 yards (meters) north of Metro North's Spuyten Duyvil station in the Bronx borough, said Aaron Donovan, a spokesman for Metro North, a subsidiary of New York State's Metropolitan Transportation Authority.
A spokesman for the city fire department confirmed the number of dead and said 11 people were in critical condition, six were in serious condition with non-life threatening injuries and another 46 sustained minor injuries.
At least one rail car was lying toppled near the Hudson river and police and other rescue workers were searching for survivors along the shoreline and the waterway.
New York Police Department divers were seen in the water near the scene of the accident, and dozens of firefighters were on the scene helping pull people from the wreckage.
Those injured were being transported to area hospitals, said New York City Fire Department spokesmanMichael Parrella.
The train was a diesel with seven cars. The locomotive was on the north end pushing the cars southward.