A two-alarm fire tore through the top floor of a six-story apartment building in Prospect Lefferts Gardens Monday afternoon, leaving dozens of people without a home.

City officials say a partial vacate order is now in place at 245 Hawthorne St., which means some tenants are not allowed back inside.

The American Red Cross says it is helping 15 households — 37 adults, 6 children, and even 4 cats and a dog — with temporary housing and emergency financial assistance.

The FDNY says the fire started just before 1 p.m. Monday. Heavy flames spread through three apartments on the top floor and into the cockloft above. More than 100 firefighters worked to get it under control, and one firefighter suffered minor injuries. Fire Marshals also arrested one person for illegally using a blowtorch. The exact cause of the fire is still under investigation.

A major obstacle for firefighters was water access. FDNY posted photos on social media showing a van parked directly in front of a hydrant. They say two hydrants were blocked, slowing their efforts to fight the fire. Blocking a hydrant is illegal and carries fines of up to $5,000.

FDNY is reminding New Yorkers never to park on or near a hydrant because seconds matter when firefighters are trying to save lives.