New Britain firefighters are investigating a two-alarm fire at Stone Hot Pizza Restaurant at 952 Stanley St. that broke out in the ceiling just after 2:30 a.m. and spread through the ducts.
An apartment building next door was evacuated because of the fire, but residents will be let back into their homes shortly.
West Hartford and Hartford fire departments were been called in for mutual aid to cover the city of New Britain in case of other fire calls.
No injuries have been reported.
Damage to the restaurant is extensive.