Cautiously, because the Star is a notoriously liberal paper that has been known to take the sides of people who didn't have much of a leg to stand on otherwise. (For example, when the Toronto PD conducted a series of drug raids a while ago that resulted in several hundred arrests without a single shot being fired, the Star's headline was all about one poor woman's children who were terrified when the police came into her home and arrested her brother, who was staying with her. Sorry, lady - not a lot of sympathy for a woman who lets her drug-dealing brother camp out on a couch in the same house as her children.) Still, I've watched the video linked in the article, and the arrest records for the protest show that these three people were never processed as having been arrested - which argues that, perhaps, they weren't. Why wouldn't they have been processed after being very visibly arrested? Maybe because the visible arrest was a smokescreen designed to hold up their cover?
Anyway, the link:
Police plant provocateurs at Montabello protests