Days before Prime Minister Justin Trudeau is set to tour Vancouver's Downtown Eastside, video has emerged of a pregnant woman overdosing in the neighbourhood. 

It shows the woman motionless on the ground near Hastings and Main, where she was first tended to by the Street Saviours, a volunteer outreach group that arrived at the scene before first responders.

"We didn't know how long she'd been down there for," said Michael Legault, one of the members involved in the rescue. "Has she been down there too long? Is there going to be permanent damage? What about the baby?"

Fortunately, through the combined efforts of the Street Saviours and paramedics, the woman was eventually revived. But for a while, things were looking bleak.

Members of the volunteer group said they administered four doses of naloxone, the opioid antidote that can reverse the effects of an overdose, to no avail.

"Usually it only takes two," said Charmaine Henry. "To give someone [more] and they're still not coming around, it was really scary."

When paramedics arrived, they administered another three doses of naloxone before the pregnant woman finally regained consciousness, according to the group.

The suspected culprit is carfentanil, a highly toxic opioid that, unlike fentanyl, is never prescribed to humans.

It was the kind of horror story Trudeau will likely hear when he visits the neighbourhood Friday, less than two weeks after the federal government pledged $10 million to help fight the overdose epidemic in B.C.

"I'm glad that the prime minister is going to see for himself because it's not isolated to Vancouver, and if it hasn't hit communities in Canada yet, it's coming," said Dave Deines, vice-president of the Ambulance Paramedics of British Columbia.

Trudeau's tour comes as the crisis continues to claim lives and drain emergency resources; last week alone, paramedics responded to 184 suspected overdoses.

First responders have admitted they can't keep up, and called on the province to hire more help. Deines said while they appreciate the efforts of pop-up support workers, they are also concerned at volunteers' lack of proper training.

"The training these people receive is nothing compared to what professional first responders and paramedics have. And in a medical emergency like that, you really need a paramedic to be at your side and treat and transport you to hospital," he said.

The Street Saviours said they’re aware of their limitations, and members always call 911 while responding to overdoses.

Until the necessary resources are available, they said they intend to continue doing their best to fill in the gaps.

With a report from CTV Vancouver's Scott Roberts