Police confirmed the identities of the two men killed during the 21st birthday celebration as Kane Wiremu Te Paa, 30, of Wainuiomata, and Chrysler Stevens-Mark, 21, of Gisborne.
A final post-mortem had concluded but police would not elaborate of the cause of death for both men, but they died from injuries sustained during the altercation.
A 25-year-old man is jointly charged with the 29-year-old who was taken into custody earlier this week.
Both arrested men were uninvited guests who arrived at the party shortly before the incident began, police said.
Police have said that while the brawl involved gang members it was not a conflict between rival gangs.
Officers have been brought in from outside of Gisborne amid concerns of further disorder.
“Further charges will be considered as the investigation into events on Lytton St, Gisborne on Saturday night progresses.
“Police will continue to have a highly visible presence in Gisborne as reassurance patrols are carried out, and work continues to support Kane and Chrysler’s families as they plan their loved one’s final journeys.
“Police will offer support to the whānau as they plan the tangi, however this is a deeply personal process and for them alone to plan,” police said.
Other information can be provided via 105, either by phone or online at 105.police.govt.nz, clicking “Update Report” referencing file number 240324/0768.
Information can also be provided anonymously by calling Crimestoppers on 0800 555 111.
Neil Reid is a Napier-based senior reporter who covers general news, features and sport. He joined the Herald in 2014 and has 30 years of newsroom experience.