A series of suspected drug overdoses left at least eight people dead over the weekend in Portland, Oregon, according to the city's police bureau.

Six of the deaths were likely related to fentanyl, a potent synthetic opioid. Several of those who died believed they were using cocaine, when it was actually fentanyl or a mix of the two substances, the city's police bureau said in a news release.

"Users are warned that there may be a batch of purported cocaine circulating on the street that is particularly dangerous to use," the release said.

The deaths occurred between early Friday morning and late Saturday afternoon. They're being investigated by the Portland Police Bureau's narcotics and organized crime unit.

Like many states around the country, Oregon in recent years has grappled with a surge in opioid overdose deaths fueled by fentanyl, a highly addictive and potentially lethal drug.

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Police in Portland, Oregon, said that at least eight people died from suspected drug overdoses over the weekend.

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Fentanyl was developed to treat intense pain from ailments like cancer. Use of fentanyl, a powerful synthetic opioid that is cheap to produce and is often sold as is or laced in other drugs, has exploded. Because it’s 50 times more potent than heroin, even a small dose can be fatal.

It has quickly become the deadliest drug in the nation, according to the Drug Enforcement Administration. Two-thirds of the 107,000 overdose deaths in 2021 were attributed to synthetic opioids like fentanyl, the U.S. Centers for Disease Control and Prevention said.

In Multnomah County, home to Portland, more than 60% of the county's 271 opioid overdoses in 2021 involved fentanyl, according to the Tri-County Opioid Safety Coalition.

That year, fentanyl also contributed to a record number of homeless deaths in Portland. Compared with 2020, the number of homeless deaths involving fentanyl jumped more than eightfold, from four to 36, according to a Multnomah County report released in February.

Statewide, the number of fatal and unintentional overdoses involving fentanyl more than doubled from 2020 to 2021, from 226 deaths to 508, according to the Oregon Health Authority. Fentanyl and methamphetamine were the most common drugs in overdose deaths in 2021, the agency found.