BROOKLYN - Four firefighters were injured battling flames in Prospect Heights overnight. 

The three-alarm fire started on the 12th floor of the Turner Towers, located at 135 Eastern Parkway. 

A worker in the building says the flames were mainly contained to one apartment. 

More than 100 firefighters were on the scene at one point. Officials say that three of those hurt were taken to Cornell Medical Center, while the fourth was sent to Methodist Hospital. 

It's unclear what sparked the blaze.