A woman died Monday in a house fire that may have been caused by burning charcoal briquettes for heat, firefighters said.

The fire was confined to one bedroom in an 87-year-old, 1,309-square-foot home in South Los Angeles, Fire Department spokesman Brian Humphrey said.

The woman was found on the floor of the locked bedroom and declared dead at the scene.

Investigators "surmise that an improper heating device, possibly using charcoal briquettes, may have not only sparked the blaze but introduced deadly carbon monoxide fumes," Humphrey said.

Fire Capt. Steve Ruda showed reporters the device — a shallow metal pan.

Temperatures dropped to the low 50s during the night, the National Weather Service reported.

It appeared gas to the home had been shut off, but Southern California Gas Co. spokeswoman April Bolduc said the utility could not release information about customer accounts.

The victim's identity, along with the cause, time and manner of death, will be determined by the coroner, Humphrey said.

The house had security doors and the bedroom was locked, but there were no bars on the windows or other factors like pack-rat conditions that would have kept a person from getting out of the home, he said.

The home also had no fire, smoke or carbon monoxide detectors, Humphrey said.

The fire, which was put out less than 12 minutes after the initial 911 call, caused an estimated $15,000 damage to the wood frame and stucco home and its contents, Humphrey said.