Residents from three homes were forced to evacuate on Christmas night after flames tore through three condo units in The Hamlet in Jericho.
First responders received calls around 10:30 p.m.
Nassau County Chief Fire Marshal Michael Uttaro says around 100 firefighters responded. Three firefighters were injured - two were transported to the hospital and one refused medical attention.
All the residents were able to get out. The Red Cross is assisting 11 individuals.
Uttaro said more than 20 fire departments responded and that it took several hours to get the fire under control.
Uttaro said drones played an essential role in battling the flames.
Fire officials say the fire does not appear suspicious, but the investigation remains ongoing.