The cause of deadly fire at the Gabriel House assisted living home in Fall River, Massachusetts last week is still officially undetermined, but investigators have narrowed it down to two possibilities: smoking or the failure of a resident's oxygen device.

More information on the cause of the deadly Fall River fire at Gabriel House on July 13 was released Tuesday. During a press conference Tuesday afternoon, officials said evidence narrowed the cause down to two possibilities, either an electrical or mechanical failure of an oxygen concentrator or the improper use or disposal of smoking materials.

The state’s fire marshal said the fire was either caused by an electrical or “mechanical failure” involving the oxygen device, or by improper use of smoking materials.