A charity worker from Brighton died in a freak accident as she tested an aerial slide at an outdoor pursuits site.
Tanya Bocking, 41, is believed to have caught her neck in a tree after her harness slipped at the Girl Guide activity centre at Blackland Farm in East Grinstead.
She had to be cut down from a zip wire, or aerial runway, by West Sussex Fire and Rescue and was pronounced dead at Princess Royal Hospital in Haywards Heath.
Ms Bocking was operations director of Brighton-based Adventure Unlimited, a charity which works with young and disadvantaged people.
She had worked at the organisation since 1999 and was a popular member of the team.
Director Richard Hardwick said everyone was in complete shock after the tragedy and family and friends were rallying round to support Ms Bocking's partner.
He said: "We are not sure exactly what happened as there were no witnesses there at the time but it seems as if something might have failed.
"She was a very experienced member of staff and knew what she was doing. She has helped thousands of children over the years.
"This is a terrible tragedy and everyone here is very upset. She was such an important part of the whole team and it is impossible to come to terms with.
"We are all like a family here and it has left everyone devastated.
The charity, based in Edward Street, has been running for 26 years. It is the first time it has been involved in such as accident.
Mr Hardwick said they would continue to work for the sake of the children the charity helps, as that was what Ms Bocking would have wanted.
Blackland Farm activity and training site, made up of woodland and fields for camping, was donated to Girlguiding UK in 1989 and takes up 122 acres.
It is often used for children's activities and company teambuilding exercises.
A spokesman for Girlguiding UK said the activity session concerned was being run by an external organisation and that none of its members were involved.
He said: "Girlguiding UK is deeply saddened by the news of the tragic accident. We would like to extend our deepest sympathies to the families, friends and colleagues of the deceased."
Mid Sussex District Council's safety and licensing department has launched an investigation.
A council spokeswoman said: "We are working with the police and the coroner's office to find out what happened.
"We don't know how long the investigation will take."
Mid Sussex coroner Barry Markham confirmed a post-mortem examination was expected to take place in the next two days.
He said: "Everything points to the fact that it is nothing other than a tragic accident."
Police are not treating the incident as suspicious.
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