Motorists heading westbound on the Upper Harbour Highway should expect delays this morning after a vehicle rolled near Hobsonville.
Two people have also been taken to hospital in a serious condition following the incident.
Footage posted to Twitter by NZTA Auckland and Northland showed the vehicle had come to a stop on its roof near the Squadron Drive off-ramp.
Emergency services were called to reports of a crash involving two vehicles around 7am this morning, a police spokesperson said.
"One of the vehicles has subsequently rolled. Two people are being taken to hospital in a serious condition. The Serious Crash Unit is in attendance."
Meanwhile, NZTA was advising westbound motorists to expect significant delays.
The left lane of the Upper Harbour Highway (SH18) and the Squadron Drive off-ramp had both been closed by emergency services.
"Expect delays in both directions as #AklTraffic slows to pass the scene," NZTA Auckland and Northland said on Twitter. Delays eastbound are from Trig Rd. Allow extra time."
One local told the Herald the incident had resulted in a massive build-up of traffic in the area.