An A train derailed as it rolled down the Central Park West express line this morning, forcing the evacuation of dozens of passengers, authorities said.

Express service on the A and D is shut down until repairs are complete, an MTA spokesman said.

No injuries were reported in the incident, which occurred at 9:02 a.m. as the train passed through the West 81st Street station.

Sources said a problem with the track caused the wheel on the last car of the A line to leave the rail.

Subway crews evacuated the passengers by backing up a rescue train to the front of the derailed train. The rescue train then brought the passengers to the Columbus Circle subway station.

Southbound A and D trains were running on the local track as crews worked to repair the track and right the derailed train.