A morning fire Sunday at Oishi Sushi on the east side destroyed the restaurant.
Damage is estimated at $500,000, said Capt. Jeff Langejans, a spokesman for the Tucson Fire Department.
A security guard reported smoke coming from the restaurant, 7002 E. Golf Links Road near South Kolb Road, just before 3 a.m.
When fire crews arrived, they found heavy smoke and flames in the attic.
As firefighters searched the restaurant to make sure no one was inside, members of a ladder company cut a hole in the roof to vent smoke, heat and gases, Langejans said.
"They found a considerable amount of fire inside the attic space and conditions continued to get more unstable," he said. "Fifteen minutes into the firefight the incident commander made the decision to transition to defensive operations and requested a second alarm."
It took 17 units and 43 firefighters 45 minutes to bring the blaze under control.
The cause and origin of the fire remain under investigation.