The Longueuil police service broke up an illegal gathering on Monday outside what they're calling a "clandestine gym" on Kimber Boulevard in the neighbourhood of Saint-Hubert, on Montreal's South Shore.
In a statement, police say the gathering of about 60 people began because a man, 49, made an online post on social media, inviting others to join him at the location.
Officers say they shut down the gym last week, but the man took down the barricade to enter anyway.
He was arrested and could face charges of mischief and obstructing the work of police.
Gyms in Quebec are expected to reopen May 31, assuming the region is downgraded to an orange zone.