Upton, MA – A report of an explosion in the area of 86 Hartford Ave South was received by the fire dispatch center around 1140hrs on December 8, 2009. As the firefighters were turning out, dispatch received a backup call from the homeowner reporting that there was now smoke and fire in the dwelling. Engine 1 was responding to the scene and radioed that heavy smoke was showing in the area of the incident. Chief 1 requested a second alarm due to Engine 1’s report of heavy smoke and fire showing from a 1sty wood framed 30x50 occupied dwelling. The bulk of the heavy fire was in the cellar and rapidly extended upwards to the living area. The first in crew stretched big lines through the side-b garage door. The crew encountered a car inside the garage with high heat conditions. The fire was now taking full possession of the first floor living area and makings its way into the attic area. Several 2 ½“and CAFS lines were stretched to attack the fire through the windows. The first floor was compromised so an aggressive interior attack was not allowed. Command pulled all firefighters out of building as the fire was now venting through the roof. Straight tip nozzles were used to penetrate water through the plastered ceiling to attempt to knock down the rolling fire in the attic space. Firefighters were able to make the roof once the heavy fire was darkened down. They set a roof ladder and sent up two hand lines to shoot water through the vent hole using a regular nozzle and a cellar nozzle to finish wetting the attic down.The firefighters were tied up on scene with extensive overhauling for hours. The occupants were transported to the hospital for minor injuries. Reports on scene were that the homeowner was possibly welding in the cellar before the fire started. The fire is under investigation by local and state agencies.