For months, fire officials said natural gas sparked the blast that brought a three-story apartment building in Borough Park crumbling down. Now, investigators say the explosion has been ruled a case of arson.

Officials say Francisca Figueroa, a tenant on the second floor and one of the two people who died, poured gasoline onto a stairwell and set it on fire.

Neighbors say Figueroa, who was the owner of Franchezka Unisex Nail Salon in Park Slope, was being evicted from her home and lit the fire as an act of revenge toward her landlord.

Figueroa died in the explosion, along with as 64-year-old Ligia Puello. 

Three other people were injured in the blast.

Relatives of Puello and Figueroa declined to speak to News 12.

The building has been completely demolished.