A bungalow was damaged in an arson attack where it is suspected fuel was poured down its front door.
Firefighters from Sunderland Central were called to Neville Road in Millfield after the blaze was spotted.
Neighbours had used a bucket of water to extinguish most of the fire, with the crew using a hose reel to put out what remained.
It is believed lighter fluid or similar was used to spark the fire.
No one was inside the house at the time of the incident, which happened last night.
A spokesman for Northumbria Police said: "At about 9.15pm police received a report of a fire from the fire brigade on Neville Road, Sunderland.
"Police attended, and the fire brigade were already on scene, where someone’s front door had been set alight.
"No-one was injured in the incident."
Police are carrying out inquiries and are appealing for anyone with any information to contact police on 101 quoting log 1134 200318 or Crimestoppers anonymously on 0800 555 111.