A large cordon was in place around the crash site. Photo / Dan Hines
Police said two people, a man and a woman, both aged 26, were taken to North Shore Hospital with serious injuries.
Whangaparaoa Peninsula residents were frustrated by the closure as residents faced long waits to get in and out of the peninsula.
The road was closed between Marellen Drive and Glenelg Road at Red Beach.
When one lane was reopened traffic was backed up more than 4km to the shopping plaza. At 90am, with the road reopened, traffic was crawling from Manly, 6km from the scene of the crash.
Red Beach resident Graeme Stokes had abandoned his car on Vipond Road and walked as far as he could, and said the queue of traffic went as far as the eye could see.
"When this road is closed we are land locked," he said.
He said the crash would make many people very late for work.
Police warned it could take some time before the road reopened. Photo / Dan Hines
He said Whangaparaoa Road was a known pinch point and traffic could be heavy, but he's never seen completely grid-locked before.
Residents frustrated by road closure
Several residents said they were frustrated by the delay of the proposed Penlink connection from Whangaparaoa to the Hibiscus Coast Highway.
Many said the traffic delays experienced today wouldn't have occurred if there had been an alternative route out of the peninsula.
One Whangaparaoa Peninsula resident said: "We have been waiting for the Penlink to happen for years. However, Len Brown has not obliged us up here on the coast. The population continues to grow and yet rate payers are not heard."
Commuters heading to the city by car were encouraged to take the Gulf Harbour Ferry instead, but the ferry captain was reportedly caught up in the traffic jam and the departure was delayed.
The crash was a head-on collision and resulted in both cars and debris being spread across four lanes, police said.
Location caused difficulties - police
Police said that because of the location of the crash there was no option to allow traffic to be diverted around the scene via a footpath as there was a bank on one side and the road dropped down to a right-of-way street on the other side.
Three investigators from the Waitemata Police Serious Crash Unit were sent to examine and clear the scene as soon as it could be done, while ensuring an adequate scene examination to allow a crash investigation was carried out.
Fuel from the ruptured tank of one of the cars was spilt across a large part of the road and that had to be cleaned up by the Fire Service to ensure the road was safe to reopen.
"At this stage we're not able to say what caused the crash, or give any possible indications as to what might have happened," inspector Mark Fergus said.
"Our thoughts are with the Jobsis family, who have received the worst news possible this morning, and their welfare is our priority."