Investigators are trying to figure out what caused a two-alarm fire in Brooklyn early Tuesday morning.

The fire broke out around 1 a.m. on the fourth floor of a building located at 529 56th Street in Sunset Park.

More than 100 firefighters responded and were able to get it under control in about two hours.  

Six families that include 19 adults and 11 children have been forced out of their home..

The Red Cross is helping them find temporary housing.