Now, the search is on to find out the cause.
Main Street in Port Washington remains closed after heavy smoke and flames forced dozens of residents out of their homes
The blaze broke out at a building directly across the street from the train station.
The firefight was immense, as more than 100 firefighters from six different departments battled well into the night to get the flames under control.
That's because the fire was burning in a hard-to-reach attic space between the top floor and the roof. Investigators are looking into reports that someone on the roof with a blowtorch sparked the fire.
In addition the damaged apartments, two businesses - a cell phone store and a Japanese restaurant - were also completely gutted.
Robert Pachtman, who owned the cell phone store, described the frantic moments after he realized the building was burning.
"I told everyone to evacuate the store, and then I ran into the apartment building," he said. "I started going up the steps, screaming and telling everybody that there was a fire going on, and I didn't know how severe it is, but fire, fire, please get out."
The Red Cross provided temporary shelter overnight for 25 adults and six children, many of who likely have no renters' insurance.