More than 25 people were hospitalized Thursday after a suspected mass overdose in Baltimore’s Penn-North neighborhood.

Five victims were reported in critical condition, while the overall number of those affected may rise as officials continue to identify additional cases.

Emergency crews treated the scene as a mass casualty incident and distributed naloxone to help reverse overdoses, the BBC has reported.

Police are treating the area as an active crime scene, and investigators are working to determine what substance was involved and the circumstances of the incident.

Written by B.C. Begley