Someone stole copper wire from PATCO's track area, leading to delays for commuters that are expected to last much of the day.
The stolen electrical cables were discovered at about 8:20 a.m., spokesman Tim Ireland said.
Trains will only be running every 25 minutes due to emergency repairs to fix the track.
The delays are expected to last much of the day and could affect the afternoon rush hour, Ireland said. He said a "significant" amount of cable was stolen west of the Ferry Avenue station, and electrical equipment was damaged.
The theft and damage were discovered through an electrical sensor, Ireland said. It wasn't immediately known when the theft occurred.