The Stuyvesant Avenue building, which also housed two apartments, will have to be destroyed, Lyndhurst Fire Chief Paul Haggerty told Daily Voice.
No one was hurt, he said.
"The fire flashed over a firefighter who thought he was burned," Haggerty said. "He was checked out and it turned out he wasn't, luckily."
A bull terrier was rescued from the building, and all of the animals were removed safely from the nearby Humane Society a few doors down.
Authorities were trying to determine the cause.
Police responding to the 4:50 p.m. call found flames shooting out the windows and front door of the office, Haggerty said.
"It's an old building with several ceilings," the chief said. "It spread instantly. We had no chance."
A brick wall kept the flames from spreading to a dry cleaners next door.
North Arlington and East Rutherford firefighters also responded, along with North Arlington EMS and Moonachie First Aid & Rescue Squad responded.
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