Harriet Nixon was killed by a falling tree branch at the Lost Paradise music festival.

The year ended in tragedy for the family of a young woman who died while setting up for a music festival on the NSW Central Coast.

Harriet Nixon, 21, was working at the Lost Paradise festival grounds in Glenworth Valley when she was struck by a large falling branch on Wednesday afternoon, according to Nine News NSW.

The Australian Nation University student had been sitting in front of the tree when the metres-long branch broke off just before 4pm, hitting her on the head.

Attendees of the three day music, arts and yoga festival - which started on Thursday and wrapped up on New Year's morning - had yet to arrive on site.

Nixon was treated at the scene by NSW Ambulance and taken to Westmead Hospital by helicopter after going into cardiac arrest.

She was in a critical condition on arrival with injuries to her head, spine and shoulders.

Safe Work NSW is currently investigating the incident.

There as been an outpouring of grief on social media for the former Oxley College student who also attended Victoria's Geelong Grammar school.

"Never have I met a young woman who was so driven, compassionate and intelligent," Serena Maree Armstrong wrote on Facebook.

"Your smile was infectious and you had a way of making everyone feel at ease. It truly was too soon but you touched many hearts and minds in the time that you were here."

While Marguerite Latham described Nixon as the "epitome of elegance with a beautiful manner and way with people I will never forget."

The ANU Hockey Club, of which she was a member, also posted a sad tribute.

Nixon's parents, Fiona and Ralph, are both longstanding members of the Southern Highlands branch of The National Party.

Details of her funeral, which will be held this Friday at Oxley College, were published on the group's Facebook page.

"The family have expressly asked for the following dress code: Colour, Pearls, R.M. Williams - and nothing black pleas," the post reads.

Meanwhile, in other worrying news for Lost Paradise organisers, a 22-year-old woman who attended the festival has claimed she was forced to drive herself to hospital after medics on site refused to treat her asthma on Friday.

A friend of Tess Jackson's wrote on her behalf in a Facebook post that the Sydney woman had been turned away because she did not have "an audible wheeze".

Jackson allegedly had to be treated overnight in hospital.

Feature image via Facebook/Lost Paradise