UPDATED 2.50PM: A 24-year-old man is extremely lucky to be alive after being shot in the face by police in Christchurch this morning.

Two officers were completing a investigation in Woolston when an unrelated person of interest appeared in a car nearby.

Superintendent Lane Todd said the 24-year-old passenger pointed a gun at the officers as they walked towards the vehicle.

Officers then made a rapid decision to shoot, wounding the man in the cheek.

Todd thinks the two constables acted appropriately, professionally and in accordance with policy.

"This was a confronting situation for them - both dangerous and dynamic," he said. "They were decisive and used their training to the very best effect."

"You can imagine that's a very serious incident for a police officer to be confronted with. It doesn't get any more serious."

"They've suffered quite a bit in terms of emotional stress."

The man has been taken into custody after being released from hospital this morning.

Three investigations are underway into the shooting, including one that's being conducted by the Independent Police Conduct Authority.