03/03/2015 03:50 EST | Updated 05/03/2015 05:59 EDT

Fentanyl pills seized in massive Project Tainted drug bust in B.C.

Vancouver Police and RCMP have seized more than 29,000 fentanyl pills, oxycodone, methamphetamine, heroin, and guns in a months-long investigation called "Project Tainted" aimed at disrupting the trade in fentanyl-laced drugs.

The investigation started in October 2014, as authorities were seeing a spike in fentanyl-related overdose deaths across B.C., and ended with the arrest of 12 people police allege were distributing the drugs.

Fentanyl, a highly potent synthetic drug, was associated with a quarter of the more than 300 drug overdose deaths in B.C. last year.

Users often think they're taking other drugs, such as heroin or oxycodone, without realizing the substance has been laced with fentanyl, which is 50 to 100 times more toxic, according to police.

"The swathe of devastation and death that's been left in the wake of fentanyl-laced drugs is unprecedented for local health authorities and police," said VPD Superintendent Mike Porteous in a release.

On Feb. 17, police executed 11 search warrants in Vancouver, Burnaby, Richmond and North Vancouver, seizing hundreds of thousands of pills, kilograms of cocaine, hash, and methamphetamine, vehicles, and a pill press.

Police expect more than 100 charges will be laid against the 12 people arrested.