The male and female who died at the scene of a crash at Mataura in Southland yesterday were back-seat passengers, say police.
The pair were among five people to die in a horror weekend on the country's roads.
Welch confirmed the unofficial road toll now stands at 24 for the year, the process that follows a fatal crash would take a month before that figure was confirmed.
At the same time last year that number was 23.
Welch urged drivers to wear their seatbelts, drive sober, keep their phones away out of reach, stick to the posted speed limit and not to drive distracted.
Today, many motorists will be making a return journey to Auckland after enjoying a long weekend away thanks to Anniversary Day.
"January is always a high risk time to be driving because the volume of traffic on our roads is at its peak," Welch said.
The driver of the crashed car and the front seat passenger were both injured
in the Southland crash.
They were transported to Dunedin and Invercargill respectively for medical
Police said as part of their inquiries into the crash, they are speaking to the driver of a second car, a red Subaru Impreza station wagon.
While that car was not directly involved in the crash, initial indications
suggest that it may be linked, police said.
Police would like to hear from anyone who saw this car - and the car that
crashed, a dark blue Holden Commodore - in the time leading up to the
The cars are believed to have travelled south through Mataura and Gore prior
to the crash.
If you can help, please call 105 and quote file number 200126/5431.
The names of those killed will be released as soon as all necessary family
notifications have taken place.
The first fatal crash on Sunday happened in the early morning in the country's far north.
A male died at the scene after his car left the road and collided with a tree in Kaitaia.
Emergency services were called to the crash on Bank St just after 6am.
A male then died in a two-vehicle crash near Lake Karapiro in Waikato.
The crash occurred on State Highway 29 shortly after 2pm.
On Saturday, one person was killed and another was seriously injured in a car crash in Waikato.
The crash happened on State Highway 1 near Cambridge, about 6.20am.
According to the Ministry of Transport, the provisional number of road deaths for 2019 is 353 from 301 crashes.