A truck's dangerous cargo is being carefully transferred from an upturned trailer north of Auckland.
The truck, carrying dangerous chemicals used in explosives, crashed about 9am, blocking a route used by traffic to miss an earlier major truck crash.
Police say the alternative route around eastern Northland coastal roads to bypass the Brynderwyn crash is impassable after a second truck went off the road.
A section of State Highway 1 at Brynderwyn was blocked after a truck and trailer rolled about 4am today. It has now reopened.
About two hours later a stock truck is believed to have gone off road while taking the Mountain Rd diversion. A tow truck which was on its way to another crash pulled the truck out.