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 State Fire Marshal revealed the possible causes of the fire that killed 10 people at an assisted living facility in Fall River.

An investigation into the source of the fatal fire at a Massachusetts assisted living facility last week classified the cause as "undetermined," though officials believe it was an accidental ignition

The deadly fire at an assisted-living facility in Fall River, Massachusetts, was accidental, but the cause is classified as undetermined.

Elderly residents – some in wheelchairs and some dependent on oxygen tanks – were blinded by deadly smoke as they tried to escape an assisted-living facility in Fall River, Massachusetts, which caught fire Sunday evening.

A fire that killed 10 people at a Massachusetts assisted-living facility was unintentionally caused by either someone smoking or an electrical issue with an oxygen machine, investigators said Tuesday.

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

Ten people have died after a Massachusetts assisted living facility caught fire Sunday night, making elderly residents rush to their windows to scream and beg for help as smoke filled the hallways.

A new initiative focused on assisted living providers is launching today in Massachusetts in response to a fire that resulted in 10 deaths.