Andrew Bagshaw's parents called their son "an ultimate humanitarian" this morning after announcing his body was found in Ukraine.
Dame Sue and Phil Bagshaw confirmed Andrew's death in a statement earlier today.
"He and a colleague, Chris Parry, were attempting to rescue an elderly woman from Soledar, in an area of intense military action, when their car was hit by an artillery shell.
"The Ukrainian authorities, and government officials in New Zealand and London have been working hard to learn more details but little further is known about the circumstances of his death."
Speaking to media after the announcement, Dame Sue said Andrew left home to volunteer in Ukraine about April last year.
"When asked when he would come back, he said 'not until it's finished'," Dame Sue said.
"He sent loads of pictures when he first went," she added. "He really stopped communicating all that regularly from about September, October. His sister felt that he was probably getting into the more dangerous work then and he didn't want to worry us.
"We would rather [Andrew] communicated but that was his way, he didn't want us to get upset."
Phil said Andrew was driven to help in Ukraine because "he was an ultimate humanitarian basically".
"He was a very intelligent man and a very independent thinker, and he thought a long time about the situation in Ukraine, and he believed it to be immoral," Phil said. "He felt that the only thing he could do of a constructive nature was to actually go and help people.
"He set off with a rucksack... and it's incredible what he achieved in a relatively short space of time."
Later in the press conference, Phil said: "We did try to convince him not to go, we rapidly realised it was a waste of time."
Andrew's body is currently in the mortuary at the Children's Hospital in Kyiv, he added.
When asked how they felt about Andrew's contribution, Dame Sue said the pair were "very, very proud" of their "amazing" son.
"He had so much talent, he would have given so much to the research world, and did...but he felt human beings were more important."
As for her message to other Kiwis thinking of volunteering in Ukraine, Dame Sue said "it's very, very dangerous".
"At the same time, it's very needed and people need to have water and food.
"The Russians in my view are committing genocide, they're starving people...it's totally immoral. War crimes go on every day."
Grzegorz Jaroslaw Rybak worked with Bagshaw on the frontlines for two weeks providing aid and helping evacuate people and animals in hard-hit areas of Ukraine.
He remembered the humanitarian aid worker as "very quiet, very alone but was doing incredible things because of the pure love of people and humanity".
"That was the humanitarian thing to do and he was doing it. It was the thing to be done and he was doing that. He was there where people should be.
"He wasn't fighting – he was helping people who had no choice. He was helping people to survive, he was helping people live their life."
Rybak called Bagshaw "one of the bravest people I have met in my life" despite the risks involved.
"They were taking the possibility that it may finish like that. But if they weren’t doing it, who would do it? We all accepted the risk and we all had to help people in an even bigger risk.
"Andrew saved hundreds of lives, I mean like hundreds, if not more."
Dame Sue urged the international community to support Ukraine, stressing that "might is not right", and also asked people not to send flowers; instead, the family request people donate that money towards Base UA, the Children's Hospital in Kyiv or UAnimals.