A Minorcan woman with reduced mobility died in a basement in Calle Vistalegre, near Porto Pi Shopping Centre on Tuesday.
Firefighters and SAMU 061 Emergency Services rushed to the scene but were unable to save the 78-year-old woman.
Investigators say her mattress caught fire when a cigarette was not put out properly.
One of the Officers at the woman's house had to be given oxygen after suffering from smoke inhalation.