Stolen cables sparked train delays in the Bronx during the Friday morning rush.
The Metropolitan Transportation Authority says around 11:30 p.m. Thursday copper cables were taken from three of the four Metro North tracks near the Williamsbridge Station.
Service on two of the tracks has been restored, but delays of about 10 minutes persisted through the morning commute.
MTA officials say removing cables is both extremely difficult and dangerous. The risks include electrocution and being struck by an oncoming train.
MTA police are investigating the theft.