The highway had been closed for much of the day following the crash just south of Hawksbury, which was reported to police about 7.20am.
The NZ Transport Agency advised about 6.40pm that the road had reopened.
Police earlier said there were reports the crash involved a truck, a ute and a car.
St John confirmed in a media alert this morning that one person was dead, one had serious injuries and another had moderate injuries.
A rescue helicopter and Fire and Emergency New Zealand crews from Willowbank, Waikouaiti and Palmerston assisted.
The road closure meant diversions were in place for much of the day. Light traffic was able to go via Coast Rd, but heavier vehicles had to either wait or take a 190km detour using SH85 to go inland at Palmerston (for those heading south) and on to SH87 to go through to Outram and from there head further south or back to Dunedin.
Around 4pm the NZ Transport Agency advised a crane was at the scene to help remove the vehicles.
The Police Serious Crash Unit had been investigating.
