A No. 6 train derailed early Monday at the Brooklyn Bridge-City Hall station, snarling the morning commute before it even began.

Two cars on the uptown No. 6 train derailed just after 6 a.m at the subway line's first stop in Manhattan, near Park Row and Frankfort Street.

There were 19 passengers aboard the train and no injuries were reported.

Crews have cleared the derailment, but the MTA warns there are residual delays on the No. 4, 5 and 6 trains.

As well, signal problems at the Bowling Green station have caused some No. 5 trains to run on the No. 2 line from Nevins Street in Brooklyn to 149th Street-Grand Concourse.

At the height of Monday morning's derailment, there were extensive delays on the No. 4, 5 and 6 trains in both directions.

All uptown No. 6 train service was rerouted and running express from Bowling Green to Grand Central-42nd Street. There was even no downtown No. 6 express service in the Bronx.

All downtown No. 6 train service was rerouted and running to Bowling Green.

Downtown No. 4 and 5 train service was running local from Harlem-125th Street to Brooklyn Bridge-City Hall.

Downtown No. 5 train service was also running local from the East 180th Street to 149th Street-Grand Concourse.

Commuters are advised to use the the 1, 2, 3, N, R and Q trains as alternate routes for travel in Manhattan and the Bronx as residual delays continue.

For more information, visit www.mta.info.