Emergency services were called to the scene of the crash, which happened at 6.15am, near the intersection of Mangakowhai Rd at Piopio.
Road authorities have issued an alert saying the road is closed in both directions until further notice.
The NZ Transport Agency's update, released at 7.31am, said motorists should allow at least an extra 15 minutes of travel time.
"The detour is not suitable for HPMV trucks," the alert said.
Northbound motorists are being told to turn right onto Ruru St, continuing onto Aria Rd and turning left onto Kahuwera Rd before taking another left onto Tikitiki Rd to return to SH3.
Southbound drivers are advised to turn left onto Tikitiki Rd, right onto Kahuwera Rd and then another right turn onto Aria Rd to get onto the highway again.
Today's road fatality comes after a person died in a single car crash near Whanganui on Saturday afternoon, about 12.25pm.
The first person to die on our roads during the holiday period was a person involved in a crash in Blenheim the night before.
The holiday road toll started at 4pm on Christmas Eve and ends at 6am on Friday.