Anderton was found unconscious about 6.30am at the side of a loading door of his horse float at the stable on Wingatui Rd.

It is understood the door landed on Anderton's chest, puncturing both his lungs and restricting his breathing

The 44-year-old's life support was switched off today.

"WorkSafe New Zealand are continuing an investigation but I surmised the hydraulics of the door failed," Constable Jason Braid, who attended the accident, said.

Anderton trained The Diamond One, a candidate for the White Robe Lodge Handicap - the feature race at the Otago Racing Club meeting on Friday. It's believed The Diamond One, Sofia Loren and Anzac Star will remain in his name for the meet. 

A minute's silence has been planned and jockeys will wear black armbands at tomorrow's Southland Racing Club meeting at Ascot Park as the New Zealand racing industry comes to terms with the news.

Southland Racing Club president Sean Bellew said Anderton's passing had shocked the industry.

"It's so sad what's happened. The club will certainly show respect and pay tribute to him," Bellew said.

Otago Racing chief executive Andre Klein described the death as a "tragic waste - a huge loss to the community here"

It was a senitment shared by fellow prominent names in the racing industry, Tony Pike and Michael Pitman.

Pike, the New Zealand Trainers' Association president said it was a "tragedy" and "to lose a young successful trainer is sad."

Canterbury Trainers' Association president Pitman, meanwhile, paid tribute to Anderton's character: "Steve was a really nice guy doing well as a trainer. It's tragic what's happened."

Before Anderton's passing, Klein said the New Zealand racing community had messages of concern flowing in from all over the country.

"Everyone just feels for his immediate family, his wife Claire and his two little kids," he said.

"Lots of trainers are very good in their own pond but he is held in huge regard across the whole country.

"He's still quite young for a trainer, he's got a number of good horses. He is a very good horseman and very patient with his horses as well," Klein noted before the death was announced.

Anderton made his name as trainer with The Jewel, winner of the Group I NZ One Thousand Guineas in 2002 and the Group I International Stakes at Te Rapa.

He trained The Jewel in partnership with his father, Hec. Others prepared by the partnership included Sand Sweeper, winner of the Canterbury Gold Cup, the Easter Cup and the Great Easter Handicap in 2005; Native Monarch (1993 Riverton Cup) and Maccadons Dream (2001 Great Easter Cup and Great Easter Handicap).

The father and son partnership provided the trifecta (first three home) in the 2005 Waikouaiti Cup with Heureka, Lydgina and O'Ella. They also saddled the trifecta three weeks earlier at Wingatui with the latter two horses and Personal Column.

Anderton trained for eight seasons with his father from 1993-2005 and worked for stables in Australia during that period. He had been working in a sole capacity for the past nine seasons after his father's retirement and added 69 wins to his tally for a total of 167. He was also the leading strike rate trainer at Wingatui twice over the past three seasons.