Police in Detroit, Michigan, are investigating whether exposure to a drug sometimes used as a horse tranquilizer caused an officer to collapse during a routine crime scene investigation.

A Detroit Police public information office representative said officers responded to a call from a business owner concerning a man who’d been shot and stabbed on Oct. 3. Investigating officers called for assistance from a hazardous materials team after a controlled horse tranquilizer drug was allegedly found in the man’s possession, the representative said.

During the investigation, a supervising officer collapsed after coming in contact with the substance and was transported to a nearby hospital for treatment.

“We are still trying to identify the drug,” the representative said and declined further comment