The three-alarm fire Sunday afternoon at DiDi's Pizza on Holaview Road in Dundalk was caused by someone placing combustible items too close to a stove, fire officials said Monday.
The fire has been ruled accidental.
More than 100 fire personnel and 30 fire vehicles arrived at the scene of the fire began shortly after noon Sunday. No one was injured in the blaze, and the fire was declared under control about an hour later, officials said.
Damages were estimated at $700,000, fire officials said.