A subway train derailed in Brooklyn on Wednesday afternoon, police and fire officials said. It was the second derailment in New York City’s mass-transit system in less than a week.

The train, a Manhattan-bound F, went off the elevated tracks between the West Eighth Street and Neptune Avenue stations in Coney Island shortly before 12:30 p.m., officials said. No injuries were reported in the immediate aftermath of the derailment and the cause was being investigated, according to the police.

As of about 1:30 p.m., Fire Department units had evacuated 17 people from the train and were removing about 20 more who were still on the train, officials said.

Service on the F line was partly suspended in Brooklyn as a result of the derailment, the Metropolitan Transportation Authority said on its website. The authority did not immediately respond to a request for information on the derailment.

The episode on Wednesday came six days after a No. 1 train carrying 300 people collided with an out-of-service train on the Upper West Side of Manhattan because of confusion over which train had the right of way. Both trains derailed as a result, and more than two dozen people were injured.