Traffic north of Whangārei came to a halt on Friday afternoon after a cattle truck was involved in an incident on State Highway 1 just north of the city.
Lengthy queues built quickly both ways after the country's main highway was closed by police; north of Hikurangi.
The road was expected to remain closed for a period of time as police are attending the scene.
Emergency services were called out just after 3pm on Friday, after the cattle truck's trailer tipped on its side.
No one was injured and no cattle were on the truck at the time.
Detours via Jordan Valley Rd and Hukerenui Rd are in place diverting the north and southbound traffic.
Police are asking drivers to avoid the area.