Police are investigating whether racially motivated violence led to a hit-and-run in Christchurch that has left two girls dead and two other people fighting for their lives.
Witnesses spoken to by the Herald have described seeing "skinheads" fighting with Polynesians around the time a car drove through a group of people outside a party of several hundred on Saturday night.
Lipine Sila, 22, is facing two charges of murder after allegedly driving through a group of people and killing Jane Young and Hannah Rossiter, both 16.
Partygoer Felix Sekulla, 17, told the Herald the street outside the 20th birthday party was calm until some groups started picking fights.
Jacob, 17, who was also at the party said fighting between the skinheads and Polynesians happened down the street from the party and many were rushing down to see it.
Asked if police would investigate the claims of racial violence, Detective Senior Sergeant David Harvey said: "That will be one of the side issues we will deal with".
Police have boosted the number of investigators on the case to at least 65 as they struggle with the "logistical nightmare" of interviewing the 250 people, whose name they have down as witnesses.
"It is possibly going to take us many weeks to talk to those people," Mr Harvey said.
Further charges against Sila may be announced on Friday.
Asked if police were concerned about revenge against Sila's family, Mr Harvey said: "We are talking to the accused's family, and we always have concerns as to the actions of vigilantes."
Text messages are urging people to attend a rally at the site of the hit-and-run this Saturday.
Mr Harvey said: "I would suggest people need to remain calm and deal with the individuals' deaths in the appropriate way, by going to funerals or memorials, without congregating in areas where potentially disorder could happen."
Two people remained in critical, but stable conditions in Christchurch Hospital yesterday, and another two were described as being in a serious but stable condition.
One of the worst injured, Felicity Tewnion, had been in an induced coma but her condition has improved.