Police have called an attack on an off-duty officer "despicable".
Acting Sergeant Nick Brunger said the Wanganui officer was on a push bike when he was waved down before being attacked.
Police believe four men were involved in the attack that took place at the intersection of Guyton and Bell
Sts, in the early hours of Saturday.
"It's a despicable act regardless of the victim's chosen career path," Brunger said. "Obviously it is close to home knowing that he is a member of the police."
Police are yet to formally interview the officer, who is recuperating at home - but understand he cycled past a group, who yelled out to him. When he turned around to talk, he was assaulted while on his bicycle.
He was knocked unconscious and suffered facial injuries. Whether his helmet saved him from more serious injuries is yet to be confirmed.
"I can confirm that he was wearing a helmet at the time of the assault and that sustained reasonable damage," Brunger said.
A 35-year-old local Wanganui man has been arrested in relation to the matter and inquiries are continuing.
Local MP and former police officer Chester Borrows said the "public would balk at such a brutal attack on a police officer.
"It disgusts me really. No one needs this. Wanganui doesn't need this."
Borrows said the attack sounded like "a pretty determined and violent assault".
The man appeared in the Wanganui District Court yesterday and was remanded in custody until Tuesday.
