Two Sanford residents were hospitalized Friday night after a fire broke out in a large multi-family apartment building on Washington Street. Two dozen people were displaced.

Authorities said the fire was caused by a woman smoking while using oxygen to help with breathing. The State Fire Marshal’s Office said Saturday that the woman, Paula Pierce, 67, was being treated at Maine Medical Center in Portland for “severe burns.”

She was listed in critical condition Saturday afternoon at the hospital. The other person hospitalized suffered smoke inhalation, according to the Sanford Fire Department, which didn’t release that individual’s name.

Neighbors heard the apartment’s smoke detector and called 911 about 8 p.m.

The sprinkler system at 17 Washington St. mostly took care of the fire, which started in the living room of the apartment of the two residents injured, Sanford Fire Capt. Brian Watkins said.

Because the building was so damaged by water, and is so large – it holds at least 20 apartments and a few ground-floor businesses – firefighters called for backup to search for residents.

“No stone was left unturned,” Watkins said.

Extensive water damage from the sprinklers forced 24 people to move out, and the Red Cross was on the scene to find them placements, Watkins said. A few businesses, including a hair salon, sandwich shop, and public accountant, were displaced, too.

Two other Maine residents have died this year from smoking while on oxygen, noted Steve McCausland, spokesman for the State Fire Marshal’s Office. “Oxygen vapors are highly flammable and those using oxygen are warned not to have any open flames nearby,” he said.

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