Auckland Transport said the intersection of Mount Wellington Highway and Longford St was affected and at 11am the incident was now cleared.
Delays are expected for bus routes.
Police said diversions were in place however motorists were advised to expect lengthy delays and to avoid travel in the area where possible.
The Serious Crash Unit has been advised.
Hato Hone St John said one person was taken to hospital after a motor vehicle incident on Mount Wellington Highway, Auckland just before 9am.
“We responded with one ambulance, one rapid response vehicle and one operations manager.
“Our paramedics treated and transported one patient in a serious condition to Auckland City Hospital.”