The fire broke out just after 3:00 p.m. inside the building at 215 Bloomfield Avenue.
There were reports that explosion preceded the fire in the kitchen of one of the buildings.
The flames broke through the roof and raced from apartment to apartment on the top floor before firefighters could bring things under control.
The fire reached 2 alarms.
The building was evacuated. No injuries were reported. Firefighters say they also got out all the pets.
Firefighters remained on the scene hosing down hot spots late Friday afternoon.
The cause of the fire is under investigation.