Investigators are looking into the cause of a fire that broke out Sunday night at New Bedford Bar and Grill.

Firefighters responded to the restaurant on County Street around 9 p.m. after a 911 caller reported smoke inside. New Bedford Fire Chief Brian Medeiros said all tenants evacuated after the fire alarm went off.

Crews encountered light smoke in a stairwell and heavy smoke coming from the rear of the 3.5-story building. Officials said people inside had tried to extinguish the fire before crews arrived, slowing its spread, and sprinkler heads had also activated in the kitchen.

Firefighters located the fire near an exhaust vent which was removed, exposing additional fire in the wall.

See more at wpri.com.