The Ontario Provincial Police is warning the public after four people in central Ontario recently died from suspected opioid overdoses.

The OPP are advising of a "highly potent and potentially fatal strain" of illicit opioids that they say may be circulating in Simcoe County and the District Municipality of Muskoka.

The OPP says officers with the Southern Georgian Bay detachment responded to a report on Tuesday of two women in their early 20s found dead of a suspected opioid overdose at a home in Tay Township.

Three days later, investigators say officers with the Bracebridge unit responded to a report of two men in their mid-40s found dead inside a motel in Gravenhurst, also of a suspected opioid overdose.

Police say the "prevalence of illicit opioids" distributed through drug trafficking networks "continues to increase."

They say symptoms of fentanyl and opioid overdose can include difficulty walking, talking or staying awake, as well as blue lips or nails, cold and clammy skin and very small pupils.