Nearly 1,000 emergency calls were handled by a single fire hall last month, and officials say fentanyl is partially to blame.

Vancouver Fire Hall 2 responded to 943 calls in May, breaking a record for most 911 calls in one month.

"The call volume is getting to levels that are unheard of," Robert Weeks, president of the Vancouver Firefighters Association, told CTV News.

"If this continues, and we expect it to continue, (the call volume) is more than a lot of municipalities have in their whole fire service, in all their fire halls."

Officials believe the spike in 911 calls directed to Hall 2, which serves the Downtown Eastside, appears to be largely due to an increase in the narcotic fentanyl.

Fentanyl is a fast-acting opioid that is 50 to 100 times more toxic than other narcotics, according to the B.C. Centre for Disease Control. The drug can be prescribed to control severe pain, but the dose must be closely monitored to prevent an overdose.

The drug has made its way to the streets, where police say it is being mixed with more expensive substances to allow dealers to save some cash. 

"Basically, drug dealers are importing fentanyl into Canada, then they're using it to create fake heroin, fake OxyContin tablets, other types of opiates," Dr. Mark Lysyshyn told CTV Morning Live on Friday.

Unsuspecting users are often unaware that they're taking a much stronger drug until it's too late.

Fentanyl is responsible for a public health emergency declared by B.C.'s top doctor earlier this year.

Despite the emergency, the number of overdoses continues to rise.

"It's hard not to get a sense of hopelessness when you don't see things getting better. In fact, you see them getting worse," Weeks said.

While the spike is most dramatic in the Downtown Eastside, the increase in call volumes is being felt across the city.

A manager at the Vancouver Dispatch Operations Centre said last year the city had 12,000 overdose and poisoning calls for the entire year. This year, they've already taken 7,000, and the year is less than halfway over.

Ambulance dispatchers have also seen a spike in 911 calls, but the increase is less dramatic. Overall, there were 464,838 calls in 2015, compared to 201,938 so far in 2016. Calls for May were up by about 2,000 in 2016, compared to last year.

In April, the number of fatal drug overdoses in the province reached 200, nearly half of the total number of deaths in all of 2015. At the time, Provincial Health Officer Dr. Perry Kendall estimated the year's death toll may reach as high as 800 if the trend continues.

Kendall said nearly half of the total deaths so far have been fentanyl-related, up from less than one-third last year.

With a report from CTV Vancouver's Scott Hurst