A police dog handler was attacked during what police say was a routine stop of a car in South Auckland.
The officer stopped the vehicle on Bairds Road, Otahuhu, about 4am.
As he spoke to the driver, two men got out of the car and assaulted him, knocking him unconscious.
Police said a truck driver scared off the attackers, and a passing ambulance crew treated the officer and took him to hospital. His condition is described as moderate.
Police are asking anyone with any information to contact them.