Toronto police say four teen boys are facing a combined 54 charges in alleged swarming attacks in city parks.
They say an unspecified number of alleged incidents happened between June 19 and 25.
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Investigators say several people were surrounded and robbed by a group of boys, in some cases at knifepoint.
They say in one instance, a suspect allegedly said he had a handgun.
Police say the two 17-year-olds and two 15-year-olds were charged on Monday.
The charges comprise numerous counts of robbery with an offensive weapon and theft under $5,000.