Service was completely halted on the B, C and M lines, and MTA spokesman Kevin Ortiz said some passengers were stranded in the dark except for phone lights.
Some riders reported a commute that measured two to three hours.
Con Edison and transit crews are working to determine what triggered the hours-long outage that affected the signals, which began around 7:30 a.m. The MTA had generators in place at the location by 11:30 a.m., allowing them to restore power.
Once the problem is identified, workers will fix it so that the system is not reliant on the generators. Delays persisted into the evening. However, trains are still bypassing the station at Seventh Avenue and 53rd Street where the outage occurred.
A, D, E, F, J, N, Q and R trains were all impacted by the outage, mostly delayed or running on different lines.
The Long Island Rail Road was cross-honoring tickets at Sutphin Boulevard-Archer Avenue, Kew Gardens-Union Turnpike, Forest Hills-71st Avenue, 61st Street-Woodside and 34th Street-Penn Station stations.
There were no injuries or evacuations reported.
Con Edison first investigated the power issue at West 42nd Street and Sixth Avenue, but did not find any problems there.
Several people took to social media to voice their displeasure: