Service on the 1 train has resumed in both directions after a derailment in Harlem on Wednesday.
Approximately 400 people were on board when the train derailed at about 5:50 p.m. near the elevated 125th Street station.
MTA officials said the cause of the derailment was still under investigation Thursday morning.
No injuries were reported, but passengers were trapped in the subway cars for more than an hour without air conditioning until a rescue train arrived.
Service was suspended in both directions between 96th and 168th streets following the incident. Service was restored Thursday morning, but officials warned that riders should expect residual delays.