The cause of a fire at a Massachusetts assisted-living facility that left 10 people dead remains undetermined for now as officials investigate whether smoking materials and an issue with a medical oxygen machine may have been factors,

The deadly fire at an assisted-living facility in Fall River, Massachusetts, was accidental, however, the cause is classified as undetermined because investigators found two possible origins, officials said.

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

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

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.

Staffing ratios, the affordability of care, and safety regulations are all being reconsidered in the wake of the Fall River blaze.

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.

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

All 273 assisted living facilities in Massachusetts will be required to send a letter to all residents and families detailing fire safety protocols.