A recent rash of fatal overdoses has Hamilton police sounding the alarm over a deadly heroin cocktail that may be circulating on the city’s streets.

Deputy Police Chief Eric Girt spoke on CBC Radio One on Monday to provide more insight on why authorities put out the warning.

“We have seen increases in the overdoses and, as I say, we haven’t determined — because the coroner has to do his work — what is causing the fatalities,” Girt told Metro Morning host Matt Galloway.

Police say they're investigating whether some blends of heroin in the city may be cut with fentanyl, a prescription painkiller that’s more powerful than heroin.

Last week, Hamilton police and public health officials announced unprecedented steps they're taking to prevent drug-related deaths and to find out what's causing the overdoses. 

The city said it would drop off overdose prevention kits to drug users’ doors. And police have offered to pick up unwanted heroin for testing, but said they won't be laying charges.

Girt defended the program, saying that while heroin use is illegal, it’s more important for police to save lives than to make arrests. 

“It’s really about public safety and harm reduction.”

Dr. Mark Weiss, medical director at Bellwoods Health Services, an addiction treatment centre in Toronto, spoke on Monday's show about an increase in heroin use he's observed among adults in their 20s in 30s.

He attributed the rise to prescription painkiller addicts switching to heroin after the province banned Oxycontin in 2012. 

To listen to the segment, click on the window at the top of the page.