Police originally responded to a report of a medical emergency at the Overlook Ridge apartments in Malden on the afternoon of Wednesday, Nov. 23, Malden Police report.
Upon arrival, officers located an unknown white substance inside one apartment. Hazmat crews were called to the scene as a response, police added.
A Facebook post from Boston's Wicked North Shore said that medical examiner was allegedly seen removing a body as well. Police did not confirm if a body was recovered.
The Department of Fire Services later determined the substance to fentanyl, Malden Police said. The area was decontaminated and there is no threat to the public, police added.
The investigation is ongoing.
Click here to follow Daily Voice Lynn and receive free news updates.