LONDON, ONT -- The province’s Special Investigations Unit (SIU) is investigating after a man suffered a self-inflicted gunshot wound as police responded to a distress call.

Provincial police in Lambton County were called to an address in Petrolia for a report of a 40-year-old man in mental distress around 7:30 p.m. Monday.

Around 10:45 p.m. members of the Emergency Response Team entered the back of the home and found that a man had sustained a gunshot wound.

The man was taken to hospital where he remains in critical condition.

Early information has led investigators to believe that the gunshot was self-inflicted.

The SIU is urging anyone who may have information about this investigation to contact the lead investigator at 1-800-787-8529.

The SIU is a civilian agency that investigates reports involving police where there has been death, serious injury or an allegation of sexual assault.