Motorists travelling over the Auckland Harbour Bridge are being advised to take alternative routes after a serious crash just after midday.
Police said a motorcyclist was in a critical condition and the Serious Crash Unit has completed its investigation.
All lanes on State Highway 1 are open, however there are significant delays.
Waka Kotahi asked motorists to consider using State Highway 18/SH16 (Western Ring Route) as an alternative route.