NEW YORK (CBS) - A propane tank and a shift in the wind; that's all it took to blow apart a home in Queens.
With its front wall buckled, its back wall blown to pieces, and bedrooms still exposed to the elements, the two-story house on Leavitt Avenue remains the focus of a joint investigation.
Neighbors in the Flushing, Queens neighborhood haven't stopped talking about the small propane tank that investigators say contributed to Monday night's powerful explosion, or what triggered the blast.
Fire officials say what they do know is that the man who lives in the home was emptying the propane tank at the back of his house, and left the door open.
"We're not sure why but he was in the backdoor. The wind must have shifted and it actually blew the propane into the house, so now we have the propane in the house. When it hit an ignition point, it blew up," FDNY Chief Edward Kilduff said on Monday.
The force of the explosion blew out the back of the building and bowed the front of it -- all after an early evening blast heard from blocks away.
"I heard a large explosion," resident Bob Kiernan said.
Kiernan and his wife rushed to the front of the building where he saw debris everywhere he looked. Then he and his wife went inside.
"We heard people screaming in Chinese," Kiernan said. "My wife is Chinese so she started talking to them from the doorway and within seconds of my calling 9-1-1 we heard sirens in the distance, so we kept telling them stay calm help is on the way."
The unidentified man and his wife, who had to be pulled from debris inside the home, both suffered non-life threatening burns and are being treated at area hospitals.
The adjacent homes also suffered damage, and both families are in shelters, courtesy of the Red Cross.