Local police say that, since January, eight people have been pricked by syringes placed inside pant pockets — mostly in stores in one of Sherbrooke's big shopping centres.
Twenty syringes have been found in all.
Two blood-filled needles were found this past weekend in two stores, including a Zellers outlet.
One of the syringes was inside the pockets of a pair of Bermuda shorts for children.
"They usually are found in the pockets of pants, they were found in jeans, Bermudas (and) not just in men's pants," Const. Rene Dubreuil told The Canadian Press. "It's a bit of everything."
The Sherbrooke police spokesman says all of the 20 syringes contained blood and that tests conducted on the first three to be analyzed reveal they contained human blood from the same person.
He would not say whether the blood was contaminated.
"For the protection of everybody and the citizens who were pricked by the syringes and who were injured, we are not saying if the blood was infected," Dubreuil said.
He also said he did not know if anyone who was jabbed has become sick.
"I can't say if they are in danger or if they became ill because it's a question of confidentiality," Dubrueil said.
Retailers are being urged to take extra time in the morning to check the pockets of pants before they open their doors.
"But also, we're telling residents and citizens to pay attention and be careful when they shop," Dubreuil said.
During a news conference Monday, Sherbrooke's police chief said people should not stop shopping.
''We have a sick person who is in the Sherbrooke area right now who is creating a certain amount of panic in all the shopping centres,'' Gaetan Labbe said.
"I think it's premature to tell citizens to stay at home.
(Written by Peter Rakobowchuk in Montreal)