Investigators ruled that an accidental fire that killed a woman in her apartment Saturday was caused by “careless smoking” near an oxygen tank in the home.

“The investigation revealed that improper use of smoking materials around home oxygen equipment started the blaze,” said Glenn Allen, spokesman for state Insurance and Safety Fire Commissioner Ralph Hudgens.

The fire, which brings the state’s fire death total to 89, was reported around 7:55 p.m.

Bystanders and family members let firefighters know someone was still inside when they arrived at the Pine Park Street address in Monroe, Assistant Fire Chief Bill Owens said in a news release.

Firefighters rushed in as heavy flames shot out through the first-floor apartment windows and front door. Shortly after getting the fire under control, firefighters found Vanessa Sheppard, 62, in the room where investigators later confirmed the blaze began.

She had limited mobility and family members told officials she smoked and used oxygen.

The fire was ruled an accident by the State Fire Marshal’s Office.

Monroe Public Safety Director Keith Glass said this apartment fire was the kind of call firefighters constantly train for but hope they never have to respond to.

“While the Monroe Fire Department knocked the fire down quickly before it spread to the adjourning apartment, this residential fire was fatal,” Glass said. “Our thoughts and prayers are with the victim’s family. The gratitude and respect I have for these public safety professionals is truly immeasurable.”

The American Red Cross is assisting two families that were displaced because of the fire. No other injuries occurred.

— Staff writer Lauren Foreman contributed to this report.