Massachusetts fire officials say smoking around a medical oxygen system was the likely cause of a fatal fire in Haverhill.
A 68-year-old man died in a house fire that started around 4 a.m. Saturday morning.
The State Fire Marshal's Office said the victim, who hasn't been identified, likely fell asleep smoking in his first floor apartment unit, and medical oxygen being used in the residence accelerated the fire.
Second floor residents were able to escape with minor injuries.
The fire marshal's office says there is no safe way to smoke around medical oxygen. Increased levels of oxygen in the environment make it easier for a fire to start and spread.
And turning off the oxygen isn't enough to lower the levels in a person's clothes, hair and bedding, either.
The state fire marshal is working with Haverhill Fire and Massachusetts State Police to determine the exact cause of the blaze.
