A fourth person has died following a crash on State Highway 8 in Pukaki, Canterbury on Saturday.
Three people were initially confirmed deceased at the scene, while a further three were airlifted in a serious condition and two had moderate injuries.
The person who died overnight was one of those in a serious condition.
An investigation into the crash remains ongoing, and police are continuing to work through formal identification processes in relation to those who died at the scene.
It is believed the fourth person to die was a Malaysian student.
It brings the Easter road toll to seven.
One of Saturday's victims was a motorcyclist travelling on the Tekapo-Twizel Road.
Malaysia's Ministry of Foreign Affairs confirmed the two others were international students at the University of Canterbury.
They were Megat Ashman Aqif Megat Irman Jefni and Wan Nur Adlina Alisa.
The pair were travelling with three others, who were all airlifted to Christchurch Hospital with a range of injuries, one of whom later died.
A sister of one of the survivors posted on X that the group were on their way to Queenstown.
The University of Canterbury said it was deeply saddened by the passing of the students.
"We know this devastating accident will have a profound and ongoing impact on our community, and we encourage students and staff to prioritise their own wellbeing, together with their whānau and friends," Vice-Chancellor Professor Cheryl de la Rey said.
"Our thoughts are with those involved in the emergency service teams, and members of the public, who responded to the scene."
The university said it would be working directly with Ōtautahi Christchurch's Malaysian community to ensure they have the support and help they need.
Malaysia's Prime Minister Anwar Ibrahim shared his condolences to the families of the two students who died on social media on Sunday.
"Condolences to the families of two Malaysian students who died in a road accident in Lake Tekapo, New Zealand," he posted on Facebook.
"I also pray for the three more Malaysian students who were injured in this incident to be healed as soon as possible."
Police are urging anyone who witnessed the crash to call Police on 105 or make a report online at https://www.police.govt.nz/use-105, quoting file number 240331/4655.
The crash has raised questions about State Highway 8. Waka Kotahi said more than 40 major crashes have taken place there in the 10 years leading up to 2020.
"Land Transport needs to take a look around those high-density areas, especially around Lake Pūkaki, round Tekapo where there's viewing places," Pūkaki Ward councillor Scott Aronson told Newshub.
"They've got to have a look at those areas and think 'are these set up the best they can be?'"
Only 90 minutes after this crash, police were alerted to a second three-vehicle crash a short distance away, at the intersection of State Highway 8 and Tekapo-Twizel Road.
One person received serious injuries and nine others suffered minor-to-moderate injuries.
An investigation into the second crash is also ongoing.
Newshub.
