Two people were airlifted to hospital following a reported assault at Warkworth Institution in Trent Hills, Ont., southeast of Peterborough.
Northumberland OPP say around 8:30 p.m. on June 10, officers attended the medium-security federal prison following a report of an assault involving multiple people.
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Police say two people suffered serious injuries, prompting an Ornge air ambulance to airlift one person to a local hospital and another to a Toronto hospital.
The OPP’s forensic identification service and crime unit continue to investigate the incident.
OPP say anyone with information is asked to call 1-888-310-1122 or provide it anonymously via Crime Stoppers at 1-800-222-8477 (TIPS) or online at stopcrimehere.ca.