No injuries were reported in the fire, which broke out at the 2½-story Noracare Wellness building on Main Street just off eastbound Route 4 shortly before 11 p.m. Saturday, city firefighters said.
Firefighters were dousing flames between the floor and ceiling when some of the drop ceiling came down, they said.
All crews were ordered out of the building as heavy fire extended to the second floor and attic.
Master streams knocked down the flames, which blew through windows and the front door.
Firefighters then returned in to douse flame pockets.
Assisting at the scene were firefighters from Englewood, Teaneck, Bogota and Ridgefield Park and in coverage colleagues from Bergenfield, Maywood, Rochelle Park and Little Ferry.
The Hackensack Fire Prevention Bureau is investigating the cause, which responders said didn't appear suspicious.
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