Exclusive: The father of a 15-year-old girl who was tragically killed in a four-wheel drive accident in WA’s south west expresses his deep pain as he struggles to envision life without her.

"I'll never walk her down the aisle, I'll never meet her first child," Greg Bragger said.

Caitlyn Bragger died when her unlicensed 16-year-old boyfriend allegedly lost control of a Land Cruiser near Logue Brook Dam on Saturday night.

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The vehicle rolled several times at Hoffman, about 150km south of Perth.

She was one of six teens in the car. Five others were injured, one of whom had to be cut from the wreck by volunteer firefighters.

Four have since been discharged from hospital, while another remains in Royal Perth.

"Their lives will go on, mine's just empty," Bragger said.

It's understood the group had been on a camping trip to celebrate Caitlyn and her boyfriend's anniversary.

Her 47-year-old father, a former army veteran, said nothing in his life had prepared him for the pain of losing his only child.

"Ten years in the army, it's nothing compared to this," he said.

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They shared a close bond, road trips, camping, even flying a Cessna when she was 10.

"She had no fear… tell her she couldn't do something, she'd prove you wrong.

"She was the world."

His final message to her before the trip simply read "Stay safe, and enjoy".

Caitlyn's death has devastated the WA community, and a GoFundMe has been launched to help the family.

Police are still investigating the crash.

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