Community group organizer Johanne Nasstrom said the incident has shaken confidence in the police in the city.
"We are very worried. We don't want them on the road anymore," said Nasstrom, who works with the Regional Table of Community Organizations.
Réjean Cormier, 61, was working his regular shift at the L'Abri de la Rive Sud in Longueuil when two police officers came in looking for a homeless man.
Cormier has been a counselor at the shelter for three years and knows the clients well.
According to Cormier, he told the officers the person they were looking for wasn't there. When he refused to let them see a list of people who were spending the night, Cormier said they beat him up.
"They threw me on the floor. They held my arm until I lost consciousness," he said.
He said one of the officers broke his arm and he needed two-hour surgery to fix it.
A spokesperson for Longueuil police said they had received a 9-11 call and the officers were looking for a person who had threatened to commit suicide.
Police said Cormier was arrested for wilfully obstructing justice.
Provincial police said they have launched an investigation but the two Longueuil police officers accused of attacking Cormier are still patrolling.