At least 15 others were injured in the mishap.
Following the crash, the car and front carriage of the train caught fire.
New York Governor Andrew Cuomo mourned the loss of lives int he mishap and tweeted: "The tragic crash of the MetroNorth train is a painful reminder how precious life is, and my prayers are with those who lost loved ones."
Westchester County Executive Rob Astorino was quoted as saying to CNN: "At this point, all indications from the MTA at least is that it was not a problem with the tracks or anything. It was unfortunately human error but that's part of the investigation."
Speaking on the investigation into the crash, the National Transportation Safety Board (NTSB) said it is sending a go-team to investigate the accident.
"Rail investigator Michael Hiller is leading the team as investigator-in-charge. NTSB Board Member Robert L. Sumwalt is accompanying the team and will serve as the principal spokesman during the on-scene phase of the investigation," NTSB said in a statement.