The woman, who has not yet been identified by police, was found late Tuesday night on a bike path between Chambly Road and Normandie Street.
Police and paramedics rushed to the scene after receiving a call around 10 p.m. ET Tuesday.
A witness was questioned by investigators.
Police are still trying to determine whether he is a suspect or if he arrived after the woman had been assaulted, said Longueuil police spokesman Tommy Lacroix.
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