(CNN) When Becca Bundy's young daughter was having a seizure at home, volunteer firefighter Bill Cox was the first person to help. Two years later, the Minnesota woman was able to offer a lifesaving thank you, by giving him one of her kidneys.
Cox has volunteered with the Bearville Volunteer Fire Department in northern Minnesota for about six years and is trained as a first responder. He got the call to help Bundy's daughter in August 2016.
"I got there and helped settle people down until an ambulance could get there and take care of her," he told CNN.
The two met again in October 2018 when Bundy went to a benefit for a neighbor at the Viking Bar, where Cox has worked for 16 years.
Cox was tending bar, wearing a bright green T-shirt that said that "My Name is Bill. I'm in end stage KIDNEY FAILURE And in need of a KIDNEY."
They talked for a bit and she realized that she had the same blood type.
"This is what started the journey. I remember telling Bill throughout my testing at one point that I knew I was the one," she told CNN.
Cox went on the transplant list in 2017, because he was born with only one kidney and that organ was failing. He went on dialysis in January of this year.
He made two of the shirts and wore them to work just about every day. He says four or five people offered their kidneys after seeing the shirt, but couldn't donate.
"She was a perfect match for me," he said.
Bundy called him with the news as soon as she heard she was a donor match.
"I can remember us both crying -- tears of joy of course -- and Bill thanking me," she said.
Dr. Raja Kandaswamy, the director of the kidney and pancreas transplant program with University of Minnesota Health, said that more than 100,000 people are waiting for a new kidney, and that list grows every year. He said that there is a huge need for donors.
"So there was an urgency for him to find a live donor, because the waiting time for an organ to come from a deceased donor could be five to seven years in Minnesota," he said.
"There was a sense of urgency to get a transplant because a 66-year-old on dialysis does not do well long-term on dialysis," Kandaswamy said. "The mortality is high once they remain on dialysis for a few years."
Kandaswamy and his team at the University of Minnesota Medical Center performed the transplant in late February.
"Since then, he hasn't looked back," said Kandaswamy. "He has great energy level, he's back to woodcarving and being a voluntary firefighter and a first responder."
The process has brought Bundy and Cox's families together.
"We continue to speak on a regular basis and do our best to get together as often as we can," Bundy said.
Before for the surgery, Cox carved a wooden angel for her and painted it her favorite color.
"She's my angel. She saved my life and I thought that would be an appropriate little gift for them," he said.