Two men suffered smoke inhalation after making a rescue attempt at a Sheffield flat that had been set on fire.
The incident happened on Fox Hill Crescent at around 11.20pm on Friday night.
A spokesman for South Yorkshire Fire and Rescue Service said a ground floor flat was set on fire and two men who feared someone could be trapped inside made a rescue attempt.
But the flat was unoccupied and the two men required oxygen and medical assistance after emergency services arrived on the scene.
He said: “Somebody has broken into the property and set fire to the middle of the living room settee.
“That then spread to the rest of the living room.
“When we got there most of the occupants had been evacuated but there were two men that had tried to gain access to see if there was anybody inside and try to put the fire out themselves.
“They suffered smoke inhalation and received treatment by paramedics on scene and oxygen from ourselves.”
The flat was substantially damaged by the blaze, with firefighters eventually leaving the scene around 1am on Saturday morning.
Crews from Elm Lane and Rivelin fire stations attended the incident.
A police and fire investigation into the circumstances of the incident is due to take place.