SAN FRANCISCO - Local health authorities in the US state of Washington are sounding alarms over fentanyl risks amid fresh reports of deaths from fentanyl-related overdosing.

Over the weekend, Public Health - Seattle & King County advised local residents not to buy drugs from street vendors or online, after three fentanyl-involved deaths were reported Thursday near the Kent-Renton boundary.

The Seattle Times identified the three victims as two men in their 20s and a 43-year-old man, adding that, during the last three months of 2019, 31 overdose deaths in King County involved fentanyl.

Health officials warned counterfeit pills bought from vendors other than licensed pharmaceutical outlets may contain illicit fentanyl that is highly likely to be fatal, citing the fentanyl overdosing fatalities in one day.

"This continues an alarming trend across the county of increases in fentanyl-involved overdose deaths from counterfeit pills," Public Health - Seattle & King County said in an alert.