Fire officers are warning it was only down to "good fortune" that a fire in an Oxfordshire flat was discovered before it spread.
Fire crews went to a first floor property at Roebuck Court in Didcot on Monday morning.
Incident Commander Steve Wright, said: "There was a smoke alarm in the flat but the battery had been removed."
The two residents were not seriously hurt in the incident but were treated by paramedics for smoke inhalation.
Firefighters with breathing apparatus used a fire extinguisher to stop it spreading from the living room where it had started because "combustibles" had been left too close to a storage heater.
Oxfordshire Fire & Rescue Service have warned that people should check their smoke alarm once a week and never remove the batteries.