Vancouver police fatally shot a knife-wielding man after they say attempts to subdue him were unsuccessful.

Officers responded to the First United Church in the city's Downtown Eastside shortly after 5 p.m. Thursday after receiving reports that a man outside was stabbing people.

Witnesses told CTV News there was an argument between three men and a woman but it escalated when one man pulled a knife. He then allegedly started slashing people with the weapon.

Sgt. Randy Fincham said officers found the suspect holding a knife on Gore Street, just outside of the church.

Officers tried to take the man into custody, and fired rounds from a beanbag shotgun in an attempt to subdue him, Fincham added.

But it was only after the suspect apparently became violent to a nearby woman that they opened fire.

"The suspect turned his attention to a woman who was standing nearby and he began to stab her," Fincham said in a statement issued to media. "Police shot the man."

He was pronounced dead at the scene.

Witnesses said three people near the church were cut during the melee: One stabbed in the head and one in the chest.

B.C. Ambulance confirms three patients were transported to hospital in critical condition. Police said the men were treated for non-life-threatening injuries, but the woman remains in critical condition.

Kellie Kilpatrick of the Independent Investigations Office says its investigators have been dispatched to the scene, calling it a “critical incident.”

Vancouver's Major Crime Section has also been called out.

Names of the victims have not been released.

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