The FDNY is investigating a Bed-Stuy apartment fire Thursday night.

Citizen app video showed heavy flames flying from the windows of a third-floor apartment in the four-story building on Hancock Street near Bedford Avenue.

The fire started around 8:45 p.m. and it took firefighters about one hour to get it under control, according to fire officials.

The FDNY said one person suffered serious but non-life-threatening injuries, and two other people were treated by EMS after suffering minor injuries.

The Red Cross was on scene assisting those in need.

The FDNY said the cause of the fire is under investigation. When asked by News 12 whether the fire was related to Thanksgiving cooking, Battalion Chief Michael McNally said it was too soon to tell.