Tyne and Wear Fire and Rescue say a large blaze which sent plumes of smoke across Sunderland city centre today was accidental.
However, fire investigators are still trying to determine exactly what sparked the fire at a scrapyard in the Sheepfolds Industrial Estate.
More than 20 firefighters from Sunderland Central, North Moor, Washington and Fulwell attended the scene shortly before midday and spent two-and-a-half hours tackling the flames.
The extent of the damage has also been revealed.
The single storey building within Ward Bros (Steel) Ltd scrap was destroyed, as well as its contents - a 1,500litre diesel tank and a number of tyres.
No one was injured in the incident.