Police have arrested a 17-year-old in relation to an aggravated robbery in the Wellington suburb of Northland

They're the second person to be charged in relation to the incident in Stellin Memorial Park on January 9, and will appear in Wellington District Court today.

Police say more arrests are inevitable, and they have sufficient evidence to arrest a third person.

They're also looking for a third offender believed to be wearing a Nomad gang jacket, who allegedly struck the victim with a machete.