Police have now identified more than 40 witnesses who were at the scene of Sunday’s double-homicide in Gisborne.

"We know there were about 100 people at this 21st birthday party when the altercation broke out, and we’re undertaking a thorough process to identify others who may be able to help," says Detective Inspector Dave de Lange.

"There are still many people who were there on the night who will have seen or heard something."

Detective Inspector Dave de Lange says if witnesses haven't yet spoken to Police, to please get in touch.

"You might think you didn’t see anything important, but even small details could be crucial to the investigation," says Detective Inspector de Lange.

"We’re also aware that videos were taken of the altercation and ask anyone with photos or footage to contact us as soon as possible."

A scene examination at the address has been completed on Monday.

The bodies of both victims were recovered from the scene on Sunday night and post-mortems will be carried out to establish cause of death.

"We are working with the pathologist to ensure whānau are reunited with their loved ones as soon as possible.

"Police liaison officers are supporting the victims’ whānau and making sure they are part of the process at this incredibly difficult time."

A 29-year-old Gisborne man has appeared in the Gisborne District Court on Monday afternoon on a charge of injuring with intent to cause grievous bodily harm.

He’s been remanded in custody and will reappear in April. 

Police continue to have a scaled-down presence at Gisborne Hospital to provide reassurance given the nature of these events.

Three people remain in hospital, two are stable and one is in a critical condition.

Police from across New Zealand are in Gisborne to support this investigation.

"This is a very complex investigation, with dozens of witnesses to interview, but everyone involved remains committed to getting answers for the grieving whānau and their community," says Detective Inspector Dave de Lange.

"Again, if you were at the address on the night, or have information that could assist, please get in touch with us as soon as possible."

The inspector says reassurance patrols in the community are ongoing.

"We know how difficult these events are for our community and how important it is for them to see us on the streets.

"We do want to stress that this is not an incident involving rival gang factions."

The inspector says that nevertheless, Gisborne Police continue to have a highly visible presence across the city, supported by their colleagues from other districts.

"We would also like to thank our partner agencies, including Victim Support and the Council, for their support and assistance."

If you have information, please get in touch with Police via 105, by phone or online at 105.police.govt.nz, clicking “Update Report”.

Please reference the file number 240324/0768.

Information can also be provided anonymously by calling Crimestoppers on 0800 555 111.