UPDATE: Smoking near oxygen tank suspected in fatal fire

RACINE -- Investigators believe smoking around an oxygen tank could be to blame for a fatal fire early Wednesday morning.

Officials say a call reporting the fire came in just before midnight Wednesday.

Firefighters saw flames showing through the roof when they arrived.

Emergency responders later found the body of Mark Halonen, 61,  in the living room, where the fire began.

\"Unfortunately the couch that he was on was consumed by the fire,\" Lt. Craig Ford of the Racine Fire Department tells CBS 58 News. \"The ceiling ended up dropping in, the insulation on top of the ceiling fell down, so it's nearly impossible to come up with the actual cigarette butt or something.\"   

There were at least two oxygen tanks that exploded and accelerated the burning process.

Firefighters say they found one tank lodged inside a window and another shot into the backyard.