The general-alarm blaze broke out at the 91 Jewell Street Apartments around 1:30 a.m. and quickly consumed the top floor and roof of the three-story multi-family building.
Garfield police forced their way in and got all residents to safety, Police Capt. Richard Uram said.
One resident was hospitalized with injuries that weren't considered life-threatening. Two police officers were treated for smoke inhalation, Uram said.
The American Red Cross relocated three families and assisted 16 other residents, the captain said.
Part of the building collapsed in the fire, which was declared under control around 3:45 a.m.
A neighboring building was evacuated as a precaution.
Firefighters from Lodi, Rochelle Park, Saddle Brook and Wallington were among the mutual responders.
The Bergen County Sheriff's Office also responded.
City Police Detective Sgt. Everett Garnto Jr. and the Garfield Fire Prevention unit were investigating the cause.
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