A three-alarm fire sparked in a Flatbush building Monday, sending residents out into the cold and leaving apartments badly damaged.

The fire broke out in a small loft between the roof and a ceiling on East 18th Street. It first broke out around 8:15 a.m., then reignited around 11 a.m.

The FDNY hasn't confirmed why the fire reignited, but says Monday's high winds were unrelated.

Fire officials say six apartments on the sixth floor sustained extensive water damage and had their windows completely blown out.

Officials say one neighbor and two firefighters suffered minor injuries, but are expected to be OK.

At least two dozen residents were forced out of their homes and were not allowed back inside. The Red Cross was on hand to provide assistance.

The cause of the flames remains under investigation.