Two city firefighters were taken to the hospital Thursday night after fighting a four-alarm fire in the Bronx.

The fire started around 8:30 p.m. inside 673 East 140th Street in Mott Haven.

FDNY officials say it started on the top floor of the six-story building that houses 50 apartments.

It took less than two hours to get it under control.­

The cause of the fire is under investigation.