TACOMA (AP) – Police say a dangerous batch of heroin or another injectable drug might be in Olympia after four people overdosed during a 90-minute period last week.

Olympia police spokesman Paul Lower says one man died Friday in a homeless encampment on the city’s west side, two others are believed to have overdosed downtown, and another man was treated following an overdose near a park.

Lower says officers are working with social service providers to warn residents about the “very dangerous heroin or opioid-type drug” on the street.