The Serious Crash Unit has been notified.
Fire and police are in attendance. Wellsford is 77km northwest of Auckland.
Six people died on the roads over Easter and police are pleading with drivers to take care when driving.
The Wellsford crash brings the road toll to 108 - at this time last year it was 94 - and police assistant commissioner for road policing Sandra Venables says many of the crashes are preventable.
"I ask all road users to take care of themselves and their passengers," she said.
"Decisions you make in your car, your truck, or on your bike impact on everyone.
"Even good drivers can make mistakes, so stay focused on getting to your destination safely.
"Make sure you're paying attention to your driving, be aware of hazards, and take a break if you're tired."
- Additional reporting: NZN