She had been told her son's body was being taken to Auckland tomorrow for a post-mortem examination.
Nelson was a "hard-working and fun-loving" man and this tragic event had "just wasted his life", Vrijs said.
"He had so much potential. He loved to cook. He was really outgoing."
Aimee Laing, who worked with Nelson, spoke to the Herald on behalf of the restaurant's staff.
Laing said Nelson had worked there for two years with three of his family members.
"His mum Dannette worked in the kitchen too, [sister] Erin worked casually in front of house and his brother Koenraad was a chef."
Laing has set up a givealittle page to raise money for Nelson's funeral costs.
"On top of this heartbreaking loss, Rob's family is not a position to pay for a funeral, and not the kind of send-off such heroism deserves," the Givealittle page said.
"They have applied for a grant but there's no guarantee this will be approved."
The page has already raised more than $2000 of the $5000 goal.
Nelson was just getting ready to start his apprenticeship to become a qualified chef.
"He loved cooking," Laing said.
"During his shift it wouldn't matter if he was five hours or five minutes in, when he saw you he always had a smile."
His sister Erin said they believed the attack was random or a case of mistaken identity by a gang. She stressed her brother was an "innocent person caught in the crossfire".
"Somebody arrived to the house and attacked about four people inside. There was another person holed up inside who wasn't injured," she said.
Her brother had died "covering his girlfriend" from the bullets, Erin said.
Detective Senior Sergeant Ross Patterson said initial inquiries suggested the house was targeted. There was no indication the wider public were at risk.
The two other victims, who also suffered gunshot wounds, remain in Waikato Hospital tonight.
The man was in a critical condition and the woman in a serious but stable condition, a Waikato District Health Board spokeswoman said at 8.30pm tonight.Social media tributes for the 23-year-old were posted online after the news of his death.
Nadine Lovini said the death was another tragedy to hit their family.
Karen Devin Tamzyn said her thoughts were with Nelson's family and Kahlee.
Stormforce Gym, of which Nelson was a member, said the world would never be the same without Nelson.
"It is with deep sadness and regret that this horrible tragedy has happened to one of our Stormforce boys.
"To his immediate family, and to his many friends, our thoughts prayers and love go out to you all at this sad time. RIP Rob, the world will never be the same without you mate."