(NECN: Ally Donnelly, Boston) - Boston Fire confirms three firefighters are still recovering in the hospital Thursday from non-life threatening injuries sustained while battling a 9-alarm blaze Wednesday that claimed the lives of two of their fellow firefighters.
Boston Fire spokesperson Steve MacDonald says nothing has been ruled in or out as investigators desperately search for what might have caused the inferno that killed Lt. Ed Walsh and firefighter Michael Kennedy.
"There was some kind of extraordinary event happened in the basement," he said.
Ken Willette with the National Fire Protection Association agrees with fire officials that Wednesday's gusting winds undoubtedly played a role in the fire's viciousness and may have obscured signs that a back draft was coming.
"That air combines with the heat, and with the fuel and will react in an explosive fire that can cause windows to fail, doors to blow, and knocks firefighters down," Willette says.
The intensity may have also chewed through fire lines, cutting off water supply.
"In explosive fire, in rapidly deteriorating conditions, all bets are off," Willette says.
MacDonald say the investigation will be painstaking and will be a process of elimination.
"You start with the obvious. You start with mechanical, you know, heating systems, electrical systems, were there smokers in the building?" he explains.
"If there's ash, they will sift through the ash and they will look for the smallest particles or the most minute piece of evidence that might tell them what might have contributed to the cause of the fire," Willette says.