A crew from Sunderland Central fire station tackled two blazes last night.
The first occurred shortly after 2am in Franklin Street, Millfield, in an extension to the Sunderland Carpet and Flooring shop.
And the second was an hour later, when fire broke out in an unoccupied flat above a shop in Ryhope Road, Grangetown.
Firefighters spent more than two hours at the scene and the flat was badly damaged.
Acting watch manager Shaun Hannah said the alarm had been raised by members of the of the public in both cases.
No-one was hurt in either incident.