Passenger train derails in New York City, killing 4

Dec. 2, 2013: Federal authorities began righting the cars Monday morning as they started an exhaustive investigation into what caused the derailment. (AP)

Dec. 2, 2013: Construction equipment operates at the scene of the derailment. (Fox News)

Dec. 1, 2013: The scene of the derailment from a hill in the Bronx. (Fox News)

Dec. 1, 2013: Officials with the National Transportation Safety Board inspect a derailed Metro North commuter train where it almost fell into the Harlem River. (AP)

Dec. 1, 2013: An aerial overview of the train derailment scene in the Bronx. (AP)

Dec. 1, 2013: Cars from a Metro-North passenger train are scattered after the train derailed in the Bronx neighborhood of New York. (AP)

Dec. 1, 2013: First responders view the derailment of a Metro North passenger train in the Bronx borough of New York. (AP)

Dec. 1, 2013: Metropolitan Transportation Authority police say the train derailed near the Spuyten Duyvil station. (AP)

Dec. 1, 2013: First responders gather at the derailment of a Metro-North passenger train in the Bronx borough of New York. (AP)

A map of the train derailment area. (Google Maps/Fox News)

Dec. 1, 2013: The locomotive of the train is seen resting on its side after the train derailed. (AP)

Dec. 1, 2013: Injured people are tended to by first responders near the site of the derailment of a Metro-North passenger train in the Bronx borough of New York. (AP)