Paralympic gold medallist Adam Hall and his family are in the "depths of despair" after the car crash which yesterday killed his number one fan - his mother Gayle.

Mrs Hall, 48, had taken Adam to Dunedin International Airport for a flight to Wellington and was returning home when her car ran off a straight stretch of road, 400m from the family home and next to the milking shed where her husband Lindsay was working.

She was trapped in the car, and died at the scene. It is understood Lindsay Hall was first on the scene.

The family have issued a short statement to the media.

"The family is obviously shocked and saddened by the loss and are basically coping one hour at a time.

"The accident has been a tragedy for the family who are supporting each other through this difficult period," the statement said.

Police are investigating the cause of the crash.

"It's gone from being the highest moment in an athlete's career, to the lowest moment within their personal life," said Paralympics New Zealand chief executive Fiona Pickering.

Dunedin Mayor Peter Chin said Mrs Hall's death was devastating.

"They were in the midst of celebrating huge success, and rightly so, and now they are really in the depths of despair."

Mrs Hall could barely watch the race in which her son, who has spina bifida, achieved gold medal glory, as the anxiety was almost too much.

But once the 22-year-old claimed top place in the men's standing-slalom ski event in Vancouver last month - edging out his boyhood idol, German Gerd Schonfelder - his proud mother and "number one fan" was one of the first to congratulate him.

Adam Hall, accompanied by Mrs Hall, Lindsay and their daughter Mikaeyla, received a hero's welcome at Dunedin airport last week when the family returned home.

Mrs Hall, described by friends as larger than life, was said to be still buzzing about her son's achievement when she dropped him off at the airport yesterday.

Adam Hall was told of his mother's death by police officers at the TVNZ studio, where he was to appear on the Good Morning show. He arrived back in Dunedin yesterday afternoon.

Family spokesman Kevin Davidson, a friend who is also a sergeant with the Dunedin police, said the family were reeling from the sudden loss of a loved mother and wife.

Mrs Hall had been looking forward to spending time with her son's girlfriend, who was visiting from the United States.

Mrs Pickering said Mrs Hall was a "very anxious mother" when it came to watching her son.

"I don't know how much Gayle actually took in of the [medal] race, because she was extremely anxious throughout the whole race. She wanted to see him succeed and live his dream.

"She was flamboyant and larger than life. The moment you would meet Gayle, you felt that you knew her immediately.

"She would welcome and embrace you as part of the whole family. She would often call me up when Adam was overseas, just to have a chat and talk about what a great lad he was - not just from a performance perspective, but she was so proud of the way he conducted himself as well."

The chief executive of the New Zealand Academy of Sport South Island, Kereyn Smith, said Mrs Hall was "the absolute rock and driver for the family. She had energy and vitality and played an important part in Adam's programmes and plans".

"Our hearts go out to the family and to Adam because his mother was always there to support him. It is a sad day ..."

Academy of Sport winter performance programme director Ashley Light was saddened by the news.

"Everyone in the winter sports industry is obviously desperately saddened. She was an inspirational lady who served not only her family but the community at large as a midwife and was an active person in the disabled community."

Colleagues of Mrs Hall, who was a midwife at Queen Mary Maternity Centre at Dunedin Hospital, were grief-stricken at the news, friend and long-time colleague Kerry Adams said.

"She had an incredible passion for midwifery and she absolutely adored her children."

Mrs Hall's colleagues had lived Adam's journey to the paralympics.

"It was her dream that he would win a gold medal and she got to live her dream. We are all just so pleased she got to see that."

Mrs Hall's funeral is expected to take place on Tuesday.

- Additional reporting Otago Daily Times