Nigel Gardner just happened to be driving down Deans Ave on his way to the mechanics as Friday's shooting was unfolding.
The shooter was standing just outside the driveway of the Deans Ave mosque when Mr Gardner realised something was wrong and people running towards him has been shot.
Mr Gardner stopped his car, putting his hazard lights on to warn other cars and grabbed his phone, he called 111 as he ran over to help people lying on the ground.
"All of the people that I saw were all shot in the back as they tried to run."
Watch Lisa Owen's full interview with Nigel Gardner here:
The road was strangely silent, other than the sound of the gun, he said.
The shooter looked at Mr Gardner but he said all he could focus on was the gun.
"I didn't think about a lot at the time, I just wanted to see if they (the victims) were okay."
A man two cars behind him had a first aid kit and they both ran around trying to apply pressure to the wounds of victims. Mr Gardner dragged one of the men behind a parked car to try to find some safety.
A five-year-old girl was among those he saw.
"Her dad was there too, he'd been shot as well, his priority was to take her, just her, to hospital. We couldn't, because we didn't have a safe way to transport her."
He said the support now being shown in the city reminds him of the aftermath of the Christchurch earthquakes.
"Everything's been put aside and we've come together as a city."