Firefighters were called to a first-floor flat in Handel Street in Westoe, South Shields, during the early hours to a report of a fire.
Tyne and Wear Fire and Rescue Service sent teams from South Shields, Hebburn and Wallsend to the scene, with four officers wearing breathing apparatus sent in to put out the blaze using a hose reel.
The fire left the door, stair case and floor boards wrecked, with the the remainder of the flat severely damaged by heat and smoke.
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A fan was also used to clear the property of fumes following the blaze.
Crews were called to the street at 1.55am on Friday, June 14.
A person who was inside the home at the time managed to get out before the emergency services arrived and was checked over by paramedics and advised to go to hospital to seek further treatment.
Engineers were called out to isolate the power and gas supplies.
Northumbria Police has confirmed inquiries are under way into the circumstances.
A spokesperson said: “At 2.20am on Friday, police were alerted by the fire service to a fire at a property on Handel Street in South Shields.
“Inquiries are ongoing.
“At this stage, police are treating the fire as suspected arson.
“Anyone with information is asked to contact 101 quoting reference 0075 14/06/19 or Crimestoppers anonymously on 0800 555 111.”