Four fire crews tackled with a large scale fire in a derelict building on North Hylton Road in Sunderland tonight.
Four engines from Marley Park; two from Sunderland and one from Washington were called to the unoccupied building around 6.15pm where bundles of clothes were set alight.
Crews used four breathing apparatus and one hose reel jet to put out the fire by 7.30pm.
A fire service spokesman from Marley Park said they were treating the blaze as arson.
No one was injured, but fire fighters are warning children of the dangers of playing in derelict buildings and are warning them they could become trapped.
Fire crews are working with police to try to establish the owner of the property.