Police want to hear from anyone who may have seen the incident or were in the general area at the time.
As part of inquiries, police are also seeking to identify the two males pictured in the above photo (wearing the denim vest and the pink singlet) and would urge both men to make contact with Hastings Police on 831 0700 or present at their nearest police station.
A crime scene was cordoned and under guard by police on Porter Drive, beside the CBD public toilets near the Havelock North Information Centre, yesterday morning.
It was taken down in the afternoon. Mr Vining said police were "following good lines of inquiry" in relation to the case.
Havelock North Community Patrol chairman Robin Deacon said the village was "generally pretty quiet" at night.
The community patrol operates up to 4am, though it was not aware of the assault.
"I'm quite surprised that something like this has happened.
"The crime activity around the village is a lot less than when I joined the patrol several years ago. In the last six to nine months it's been pretty uneventful."
Mr Deacon said much of the night activity in the village revolved around Turks Sports Bar, Loading Ramp and Diva Bistro and Bar, which closed between 1am and 3am.
"Of course everybody disperses from there and the ones that are left walk down to McDonald's. There's been the odd skirmish in the village, particularly on closing time, but nothing to the extent [of the assault]."
Havelock North Business Association president Sam Jackman said he believed the assault was "an isolated incident".
"I think the village generally is a very safe place. We get antisocial behaviour every now and then, but we're a tight community."
Patrons at Havelock North's hotels and restaurants were generally well-behaved, Mr Jackman said, and retailers operated responsibly.
"It's unsavoury elements coming into the village, which is unfortunate.
"Police resources are stretched at that time of day and it's unfortunate this happens in a small community like Havelock North."