ARSONISTS set fire to a telecommunications box.
The incident happened in South Street, Usworth, Washington, at about 10pm on Tuesday.
A concerned member of the public dialled 999 after spotting the blaze.
One crew from Sunderland west station in Washington attended the scene, where firefighters located and put out the blaze.
Fire crews said the fire had been extinguished by 11.15pm and the area was made safe.
Anyone with information can contact police, tel: 101.