Emergency services were called to the accident about 4.20pm.
“Indications are there have been serious injuries,” police said.
Police said traffic management is currently in place and motorists are advised to expect significant delays.
“Please avoid the area if possible.”
A Wellington Free Ambulance spokesperson said one person in a serious condition and two people with moderate injuries were transported to Wellington Hospital.
A further four patients were treated at the scene and didn’t require transport for further treatment.
At 5.30pm, NZ Transport Agency Waka Kotahi said SH2 had been reduced to one southbound lane just prior to Ngauranga because of the crash.
“Significant delays are present city-bound from the Hutt Valley, with queues present between Dowse Dr and Ngauranga.”