A three-car crash has blocked several lanes of State Highway 1 north of Auckland, causing significant traffic delays. 

A police spokeswoman said the crash, shortly before 3.30pm, happened near the turn-off to Schollum Access Rd at Pohuehue. 

All occupants were out of their vehicles but there were no serious injuries and an ambulance had been declined, the spokeswoman said. 

The crash reduced the highway to one lane. Google maps data show there are significant queues of traffic southbound for about 3km.