The National Transportation Safety Board will remain at the scene of a deadly Metro North train derailment for a week or more to help determine the cause.

Four people were killed and more than 60 others were injured when the seven-car train out of Poughkeepsie skidded off the tracks around 7:20 this morning in Spuyten Duyvil, nearly ending up in the nearby Harlem River.

NTSB Boardmember Earl Weener says agency members will gather tonight to split up into teams to focus on track conditions, signals, mechanical equipment, operations, human performance and survival factors.

Once the NTSB finishes its investigation, the site will be turned over to the MTA to commence repairs. A crane is in route to right the trains that are part of the probe. 

Governor Cuomo cautions Metro North riders impacted that Monday morning's commute will be long and urges them to use the Harlem line. (Metro Network Inc.)