Baking soda and talcum powder were found in five suspicious packages after a number of streets were closed while emergency crews investigated.
The first call came just after 12:30 p.m. Tuesday at 21st Street East between 4th and 5th Avenue after a suspicious package with a white substance was dropped off to a restaurant.
Over the course of the next two hours, similar reports came in from two other downtown buildings on 4th Avenue, and a hotel and motel just north of Circle Drive on Avenue C.
Inspector Lorne Constantinoff with Saskatoon Police says the short time span caught police off guard.
Two women and a man were taken into custody.
They are facing five charges each of public mischief, mischief, and utter threats to cause bodily harm.