"I just saw it and jumped out of the car, ran across the road and found one of our other constables and the guy in a recovery position,'' Welton said.
"We made the decision to do CPR and we did that for a while. Another officer went to a nearby supermarket in search of a defibrillator.
"We just shocked him and continued CPR. That went on for about seven minutes.
"I've never used a defib on someone. I've seen it being used, but never actually had to be the person to put it on and actually push the button - which is quite a different experience."
Welton, 23, has been in the job for about two and a half years, she said.
"I was in that [thinking]: 'Oh my gosh, I actually have to do this now'. Your training just kicks in - your adrenaline's up and it all just kicks in, really.
"I just got past it. I'm a volunteer firefighter. I just took the command and just did it."
Being able to help a person in that situation was still a huge highlight.
"Being able to go to a potentially fatal car accident and it not turning out like that.
"It's not often you do CPR on someone for so long and they survive it. It was really cool being able to do CPR and use a defib and get a result from it. I want defibs in our cars now."
A Waikato Hospital spokesman said late last night the man remained in a critical condition and was in the intensive care unit.
Sergeant Darren Hayes said police were hoping to arrange for the officers involved to meet the man and his family at some point.
"From everything we've heard from the staff at the hospital, it was the difference of him living - which was awesome.''
