Emmeline McKinnon said outside court in Hamilton in New Zealand that the worst thing was telling her mother her brother was gone.

She said her brother's fiancee had been "amazingly resilient and strong".

"I cannot even begin to understand what she's gone through," Ms McKinnon said.

"She's a really strong young woman. We're just really glad she's alive."

Detective Inspector Graham Pitkethley said Ms Buckley remained shocked and traumatised from her ordeal.

"She is thankful that an arrest within a 24 hour period has occurred and we're working with her and her family and we'll continue to be in touch with her around her welfare," he said.

Police revealed they are still searching for the gun used to kill Mr McKinnon as a man faced court over the random attack.

They said there were also working to return his body to his family in accordance with their wishes.

Police also urged anyone who may have spotted hitchhikers around Waikato township Gordonton or at nearby Whitikahu during the day on Friday to contact them.

Mr McKinnon's alleged killer, whose name has been suppressed, appeared in the Hamilton District Court on Saturday charged with offences including murder, aggravated robbery and making threats to kill.

EARLIER:

A man has been charged over the murder of Nirranda surfer Sean McKinnon, who was shot while travelling with his fiancee in New Zealand.

Sean McKinnon, 33, was shot dead in a campervan on Friday during a random attack in Raglan, outside Hamilton.

A 23-year-old man was arrested at a rural Waikato address on Friday night, following a tip-off from the public.

He will front Hamilton District Court on Saturday charged with murder and a number of other offences including aggravated robbery and making threats to kill.

New Zealand police Detective Inspector Graham Pitkethley said police weren't looking for anyone else in relation to the attack.

"The homicide inquiry still continues, and there is work that will still be undertaken in and around the Waikato district as we work through to reconstruct the full events of this tragic event," he said in a press conference in Hamilton on Saturday.

READ more: Much loved surfer, musician shot dead

Mr McKinnon was killed while sleeping in the van with his Canadian fiancee Bianca Buckley, in the renowned North Island surfing town of Raglan.

The gunman allegedly ambushed the couple after 2am on Friday, demanding the keys to the campervan before shooting Mr McKinnon.

Ms Buckley managed to escape on foot in the dark to a nearby farm for help while the gunman drove off in the campervan, with Mr McKinnon's body inside, police said.

Mr McKinnon's body was found in the van, which was abandoned in Hamilton, about 80km away.

"She is obviously shocked and traumatised," Detective Inspector Pitkethley said.

"She is thankful that an arrest within a 24-hour period has occurred and we're working with her and her family, and we'll continue to be in touch with her around her welfare."

Detective Inspector Pitkethley said police weren't looking for anyone else in relation to the attack.

"This is a random, tragic event," he said.

Mr McKinnon's family arrived in New Zealand overnight and were pleased to hear of an arrest, Detective Inspector Pitkethley.

"We know this was an alarming incident that shocked people right across New Zealand and overseas," he said in a later statement.

"We want to reassure the community that the safety of our community is our priority and we will do everything we can to find those responsible for serious crimes and hold them to account."

People from all over the world have expressed their shock and sadness online.

One person took to Facebook and said: "I am so saddened for you - what a random horrible attack. Much love to you and your family."

Another person said: "I did not know you. But I'm so very saddened upon hearing of another tragic event that destroyed the lives of two young people enjoying life together. My deepest condolences to Sean and his family, as well as to his fiancé. May you both find peace."

The homicide investigation still continues.

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