ROSELLE PARK — Police are investigating how a smoke bomb went off at a McDonald's restaurant on Friday afternoon.

The grenade-shaped device went off about 4:30 p.m. in the men's bathroom and filled the crowded restaurant with smoke, according to police Chief Daniel J. McCaffery.

The eatery on Westfield Avenue was evacuated and nobody was injured, McCaffery said.

McCaffery said police are trying to find out what happened. The chief asked anyone with information about the incident to call his department at 908-245-2300.

At least two other McDonald's in New Jersey have been the site of mischief and fights in 2019.

Someone released a rat inside the McDonald's on Broad Street in Newark in February, causing customers to scream and run as the white rat sat on the floor.

A fight between two women inside the McDonald's on South Arkansas Avenue in Atlantic City escalated quickly in March with customers throwing trays and bags at employees. One of the women sprayed a security guard with pepper spray.