SH1 was closed for seven hours after the crash before reopening at 3.30am.
The Serious Crash Unit is investigating and police are providing support to the drivers’ families.
Meanwhile, State Highway 6 was closed as a truck hauling dangerous materials dangles over the edge of the road in Tasman.
A police spokesperson said SH6 was closed in both directions after the crash at 4.40am.
The road was closed for four hours before it was reopened at 8.25am.
The truck veered off the road and crashed into the barrier between Central Rd and Hori Bay Rd.
Police said there were no reported injuries or damage to the truck’s load.
“Due to the position of the truck, which is hanging over the edge of the road, both lanes have been closed while a heavy tow is arranged.
“The road is expected to be closed for some time and the only alternative route is through St Arnaud. Motorists are advised to expect delays and check NZTA’s Journey Planner website for latest road conditions.”