An alert police officer spotted heavy smoke from a Broadway building Saturday night, prompting evacuations before firefighters quickly extinguished a roof fire, officials said.

The fire was reported at 7:17 p.m. at 957 Broadway, where a Bayonne officer on patrol saw smoke from the roof, called in the alarm and activated fire alarms to alert residents, according to Fire Chief Keith Weaver.

Arriving fire crews found a small blaze on the roof and used a hand line to extinguish flames contained to a planter box and part of the roof structure. The building’s occupants and an on-site restaurant were evacuated until the fire was declared under control at 7:34 p.m.

No injuries were reported. Damage was limited to a small section of the roof deck. Investigators said the fire appeared to be accidental in nature