The blaze began around 10:10 a.m. Sunday, May 19, at the two-story structure in Norwalk.
The building had a Mexican eatery on the first floor and apartments on the second floor at Liberty Square.
When responders arrived at the scene, heavy smoke was coming from the roof, with flames coming out the top of a large kitchen exhaust system, the Norwalk Fire Department said.
The fire, located in the kitchen exhaust system, had extended into the floors and walls of the second floor.
After extensive overhaul, the fire was extinguished in about an hour by a two-alarm assignment consisting of four Engines, two Ladder Trucks, one Heavy Rescue, and the deputy chief, totaling 29 personnel.
There are currently two occupants displaced by the fire.
The restaurant and a second-floor apartment sustained moderate damage.
There were no reported injuries to firefighters or civilians.
The Norwalk Fire Marshal Division is investigating the cause of the fire.
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