Police investigating the gang slaying of Whanganui Mobster Kevin Ratana have made eight arrests.

The group were arrested yesterday and face charges including threatening to kill, unlawful possession of ammunition and participation in an organised crime group.

"As the homicide investigation continues we expect to lay further charges," Detective Inspector Ross McKay said.

Police had cordoned off Tiki St yesterday, which is around the corner from where Ratana,a Mongrel Mob member, was shot dead.

Ratana, 27, was gunned down in Puriri St, Castlecliff about 9.40am last Tuesday morning, amid reports of a gang clash in the suburb.

The offenders remain on the run, however it was believed those involved were known to each other and were known to police.

His tangi began yesterday and police drafted in extra resources, including the police Eagle helicopter, as more gang members arrive in the city.

Police have promised a "high visibility" presence in Whanganui over the next few days.