Investigators may never know for certain what sparked the fire on the left side of the U-shaped assisted living facility.

Investigators say a fire that killed 10 people at a Massachusetts assisted-living facility was likely caused by smoking or an oxygen machine's electrical problem. The Massachusetts fire marshal,

River fire union has claimed more lives could have been saved if more firefighters were on scene. The mayor says the department was staffed as requested by the chief.

More than 75 percent of Gabriel House residents are enrolled in Medicaid, state officials have said, and it charges significantly less than a typical assisted living facility does for private-paying patients.