Eighteen people have died on New Zealand roads since Monday, with at least six of them under the age of 18.

Seven people have been rushed to hospital after a crash that left a highway blocked in Stoke, near Nelson.

Police said several vehicles collided at 4.10pm on Whakatu Drive, State Highway Six.

The crash left the southbound lane of the road blocked.

Earlier, eight people were injured in a crash on State Highway 30 at Rotoma in Bay of Plenty.

Drivers are being warned to stay vigilant after one of New Zealand's worst weeks in road history.

Eighteen people have died since Monday, at least six of them under the age of 18.

The AA's road safety spokesperson Dylan Thomsen said it was not just drunk drivers or people speeding that caused crashes.

"I think people do get quite casual and blasé about the risks that are out on the roads. But the other thing is that there is no silver bullet, there's no easy answer that will fix all of this."

Associate Minister of Transport Julie Anne Genter said more work needed to be done on enforcement of road rules.