A three-vehicle crash on Auckland’s Northern Motorway which left three people injured has caused traffic chaos as holidaymakers leave the city for Anzac Day and the weekend.

NZ Transport Agency Waka Kotahi said the crash on the State Highway 1 northbound lanes had earlier blocked the Stafford Rd off-ramp.

Police said the crash involved three vehicles and was reported about 2.40pm.

“One person has been assessed as being in a serious condition and will be transported to hospital. The off-ramp has been closed while the scene is cleared.

“Northbound traffic on SH1 is advised to take an alternative off-ramp in the interim,” a spokesperson said earlier.

Congestion across the Auckland Harbour Bridge after a crash near the Stafford Rd off-ramp on the Northern Motorway. Photo / Google

The Stafford Rd off-ramp was cleared at 3.45pm and all lanes have re-opened.

Hato Hone St John received a call at 2.35pm about an incident on the Northern Motorway, near Northcote Point.

“We responded with two ambulances and one rapid-response vehicle.”

Three people were transported to North Shore Hospital, one in a serious condition, one in a moderate condition and one with minor injuries.

Fire and Emergency NZ (Fenz) said it sent three fire trucks to the crash.

Traffic has backed up from the crash and across the harbour bridge, live Google traffic data shows.

NZTA earlier asked motorists to use an alternate route though traffic was now flowing again.

A passing motorist said there was a “huge crash.

“Pretty frantic scene with officers rushing around and what appears to be a Prius absolutely demolished.”

Police have urged commuters to take care during what is certain to be a “busy long weekend on our roads”, with many people expected to also take Friday off.

“It’s the second long weekend in under a month, after the Easter break, but the message remains the same for people behind the wheel to do their relaxing once they’ve finished driving to their destination,” police said.

NZ Police director of road policing, Superintendent Steve Greally, cautioned Kiwis getting in their vehicles to drive in the dark to Anzac Day dawn services, particularly those in unlit rural areas.

“Those split-second decisions when driving can put a life in the balance... our officers will be on our roads to ensure drivers are driving safely.”

NZTA road safety manager Fabian Marsh urged commuters to “drive to the speed limit, don’t drink and drive, make sure you’re rested, and plan ahead”.

“We want you to get to your friends and whānau safely.”

This article was originally posted on the NZ Herald here.