Fire officials identified an electric baseboard heater as the origin of Wednesday morning’s fatal apartment fire on Prospect Street in Cambridge, according to a statement from the state fire marshal released Thursday.
Officials said the heater might have malfunctioned, had an electrical wiring failure, or someone may have set items on it that caught fire, according to the statement.
A woman in her 50s died in the fire. She was believed to have been a guest of the apartment’s tenant.
The name of the woman will be released after her family is notified, according to the statement.
The smoke alarms inside the apartment, and many others in the building, were disconnected or without a battery, Cambridge Fire Chief Gerald R. Reardon said in the statement.
“A working smoke alarm coupled with an escape plan can double one’s chances of surviving a fire,” he said.
The three-alarm fire caused about $400,000 in damage to the building and $50,000 damage to the building next door.
Seven people were displaced, said the statement.