"I ran over and saw a lot of blood on the footpath, and that he had a shotgun wound in his side."
The man on the footpath was Shon Tyson Wanahi, 26. A second man, Bunji Fenton, 27, was shot in the arm on Railway St, outside the station.
The gunman was still on the loose but Te Kotahi didn't hesitate to pull off his shirt and plug it into Wanahi's wound.
He also instructed the train station security guard to call police.
"We had a refresher St John first aid course the day before," Te Kotahi said.
"They asked what should you do if someone's been shot and I suggested taking the shirt off your back.
"We were all laughing away at the thought of me taking my shirt off. I didn't think I'd have to the next night."
The 51-year-old Manurewa man, who has volunteered as a warden for four years, said helping Wanahi was "automatic".
"What I'd learned the day before was still fresh. He was moaning and wincing but I kept applying pressure.
"I didn't think about my own safety ... Not until the cops arrived with guns and they moved me to a safe area."
Wanahi was taken to Middlemore Hospital but was pronounced dead. Fenton was taken to hospital in a serious condition and was stabilised by medical staff.
Te Kotahi was given a Certificate of Appreciation by Counties Manukau Police in recognition of his "bravery and meritorious actions" at a police awards ceremony on Friday.
"I'm not the type of person who likes getting awards," Te Kotahi said.
"I asked if my girlfriend could get it for me, but I was told that's not how it works
"Some of the wardens and my son have come. I think they think it's quite cool."
Bay of Plenty man Isaac Cruz Eru Broughton, 28, has been charged with murder and causing grievous bodily harm with intent to do so in relation to the incident.
His name suppression was lifted in June.
Broughton is due back in Auckland High Court on August 3.
