LONDON, ONT. -- The province's Special Investigations Unit (SIU) has invoked its mandate after a man suffered life-threatening injuries during an incident involving police.

Around 10:30 a.m. Monday, London police were called to Greenway Park for a man with a possible handgun.

Officers closed Wonderland Road in both directions between Springbank and Riverside, as well as the footpaths in the area.

Around 12:15 p.m., a 24-year-old man was rushed to hospital with life-threatening injuries.

According to the SIU,  five investigators and two forensic investigators have been assigned to the case.

The SIU is asking anyone with information or video of the incident to call 1-800-787-8529.

The SIU is an arm's length agency that investigates events involving the police that have resulted in death, serious injury, or reports of sexual assault.