Vancouver police issued a public warning Monday to drug users after two women died from what they suspect is a lethal form of heroin in circulation.

"It's a heroin that's potentially deadly," Const. Lindsey Houghton said. "Either it's cut with an unknown substance or of such purity that it's potentially more deadly than usual."

Houghton told ctvbc.ca that two women, aged 18 and 26, died of possible heroin overdoses last week in East Vancouver.

"We haven't received toxicology reports but evidence strongly pointed towards a heroin overdose," he said.

The body of a 26-year-woman was found behind a Petro Canada gas station on Kingsway and Nanaimo streets Thursday evening.

The next night, the body of an 18-year-old woman was found inside a building less than one block away on Kingsway, according to Houghton.

In a third case, a man injected heroin that was cut with an unknown substance and experienced very serious side-effects.

Police have not identified the source of the heroin.

Houghton says that drug users should seek medical attention immediately if they feel unwell and use the services of Insite, a safe injection site, where medical staff can assist if there are problems.