An extensive police operation is under way on a street in Christchurch's Northcote - where four people were injured last night, reportedly in a gang-related altercation

Emergency services were called to Hoani Street about 9.30pm.

Police say one person's critically wounded - and another seriously.

Canterbury District Commander Superintendent Tony Hill says it's believed the parties involved knew each other.

Herald reporter Jazlyn Whales is at Hoani Street

She says there are multiple smaller cordons within the larger barrier - and three or four homes are separately roped off.