No injuries were immediately reported.
The two-alarm fire broke out in the ceiling between the Mezza Luna Bistro on West Allendale Avenue and a residence above around 8:30 a.m., responders said.
Firefighters who were met with heavy smoke knocked down the blaze, then doused additional flames found during the overhaul.
The fire damaged the restaurant and temporarily closed adjoining businesses.
Firefighters from Franklin Lakes, Ramsey, Upper Saddle River and Waldwick assisted.
Two weeks ago, a SWAT team broke into an apartment above the restaurant and seized a man who purportedly threatened to shoot someone.
SEE: Allendale Business District Blocked Off, SWAT Team Seizes Troubled Man In Shooting Threat
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