The deadly synthetic painkiller W-18, considered 100 times more toxic than heroin, has surfaced in Vancouver.

The drug, initially thought to be counterfeit Oxycontin, was seized by police in April at a West End apartment building as part of a break-in investigation, police said Tuesday.

But investigators received the results of Health Canada testing on Friday that revealed it was actually W-18. Two men have since been arrested.

Officers are warning habitual and recreational drug users that they’re at even greater risk.

“We continue to see an alarming increase in overdose deaths throughout the province,” said VPD Sgt. Randy Fincham. “Many of those deaths have been the result of people knowingly, or unknowingly, taking synthetic painkillers such as fentanyl.”

Last month, Delta Police announced they had arrested two Lower Mainland men after busting a fentanyl lab inside a Burnaby condo. The eight-month investigation also led to the seizure of more than $1.5 million, 125 grams of pure fentanyl, 16 kilograms of cocaine, and 4,500 oxycodone and oxycontin pills.