After three opioid overdose deaths in the previous two days, the Duluth and Hermantown police departments on Monday issued a renewed warning about the dangers of opioid drugs.

Police said in a news release they are “concerned for opioid users,” and warned people of the risk of using the drugs “as their content and purity are often unknown and can cause overdose deaths.”

Authorities did not provide further details on any of the people who have died in the past two days, or the circumstances of those deaths. The deaths are currently under investigation.