The fire started early Sunday in a two-family home on Cedar Street in Sleepy Hollow and quickly engulfed a neighbor's house.
The fire was raging out of control as the families who lived here struggled to escape.
Sleepy Hollow Fire Chief John Korzelius says they barely made it out alive.
Investigators were suspicious from the very beginning. The fire started just beneath the front porch, next to the home's natural gas line.
They say it may have been an attempt to blow-up the house while the tenants were asleep and to block their main escape route, if they survived the blast.
Sleepy Hollow Police Chief Gregory Camp says samples of the debris are being tested for accelerants.
Investigators are also studying several videotapes for clues.
The fire quickly spread to the building next door and a total of nineteen people lost everything they owned.