A fire chief confirms a worker had been using a blow torch in one of the buildings in Richmond Hill.
The flames went from one building on Jamaica Avenue to the next, keeping firefighters busy and drawing a big crowd watching.
At one point, an explosion in the empty space between the ceiling and the roof pushed down the ceiling.
Firefighters inside were pulled out in case the ceiling collapsed.
In the end, there were only four minor injuries reported.
A number of families lost their homes and are being helped by the Red Cross. Eleven people are reportedly being provided emergency housing.
Grace Sukhra couldn't take her eyes off the fire, which borke out in the building wher she works as a medical assistant.
"I started smelling the smoke," she said. "My coworker didn't. We were with a patient. Good thing someone came knocking on the door and said you need to get out right now."
Just when it seemed under control, there was another dangerous flare up.
"A smoke and fire explosion occurred," FDNY Chief Edward Kilduff said. "It pushed the ceiling down on the members that were operating inside and at that time the commander felt they might be trapped inside."
Evelyn Lopez said friends called her to make sure she wasn't hurt. She rushed home then watched as her second-floor apartment went up in flames.