The province's Special Investigations Unit is investigating the shooting death of a 52 year old in Port Colborne.
Sunday morning at 9 a.m. Niagara Regional Police were called to the Main Street West and Canal Bank Road area for a neighbour dispute.
The SIU says when police arrived one person of interest had barricaded himself inside.
The Emergency Task Unit and a negotiator also responded.
At about 2 p.m. the ETU forced their way inside the apartment and one of the officers shot and killed the man.
The SIU is urging anyone who may have information including video or photos, to contact the lead investigator.