WELLINGTON, March 9 -- The military has been called in to help capture an armed person who shot and wounded four police officers in an incident in the Bay of Plenty, on the east of New Zealand's North Island, Wednesday, said the New Zealand Police.

The four officers were sent to hospital and one was reportedly in a critical condition.

Police initially said three officers had been shot, but it later emerged a fourth had been injured.

Deputy police commissioner Mike Clement said in a broadcast press conference that only one offender was thought to be involved.

Late on Wednesday, police were still in a standoff with the alleged offender, who was in a rural house on a road just outside the town of Kawerau.

The police Armed Offenders Squad was at the scene and police had asked the New Zealand Defence Force (NZDF) for assistance.

The NZDF had provided one NH-90 tactical lift helicopter and three light armoured vehicles, Clement said in a statement later Wednesday.

Police had been in the area in the morning to seize illegal cannabis when the first shots were fired.

All the injured officers were men, he said.

Two were in a stable condition in hospital, the third in a critical condition, and the fourth was receiving treatment for a gunshot wound to a hand.

The head of the New Zealand Police, Commissioner Mike Bush, had cut short a work-related visit to Australia to return to New Zealand and oversee the operation, said the New Zealand Police Twitter account.