Regina police say xylazine was found in a substance tested at the Newo Yotina Friendship Centre’s drug testing site.
Xylazine is a tranquillizer used in animals by veterinarians.
In humans, the drug causes sedation, muscle relaxation and unconsciousness.
Its effects cannot be reversed by administering naloxone.
According to police, traces of the drug were found in a tested substance that was believed to have been sold as fentanyl. Fentanyl was also detected in the drug.
The combination has a high risk of overdose and death.
Police said they believe the drug to have come from a larger batch that is likely circulating in Regina. They said it was purple.
In a media release, police asked the public to be aware of the signs of overdose and carry and know how to properly use naloxone.