DUNLAP, California (CNN) -- Even if his daughter was fearless, Paul Hanson was not. He supported Dianna's lifelong love of big cats, as well as her single-minded mission to work with them. Yet despite her assurances, he worried.
His nightmare came true Wednesday, when a 350-pound African lion killed Dianna Hanson at Project Survival's Cat Haven in Dunlap, California, where she was working as an intern.
"I always had a premonition that someday I would get a call like this," her father said Thursday. "But I just thought it would be much further in the future than 24."
That's how old the Seattle native was when the lion opened the gate of a pen at the big cat sanctuary, then moved into a larger enclosure, according to the local coroner.
Dianna Hanson was cleaning the enclosure the two lions had been in not long before, Fresno County coroner Dr. David Hadden said, citing investigators. Somehow, one of those animals -- a 5-year-old lion named Cous Cous -- escaped and attacked her.
"(Hanson) died very quickly and did not suffer," Hadden said.
A preliminary autopsy showed Hanson died of a "broken neck and other neck injuries," according to the coroner. The animal inflicted other injuries "post-mortem."
Paul Hanson,told CNN's Erin Burnett he had been told that his daughter wasn't mauled, saying she had no blood, "no rips or gashes."
He and his family are grieving, taking comfort in the fact that Dianna Hanson died doing what she loved -- taking care of big cats such as Cous Cous. Looking back at photos Dianna had posted on Facebook over the past two months, when she'd begun working at the expansive northern California facility, Paul Hanson said he and his wife agreed that this was the happiest they'd ever seen her.
"And that's the only way I can bear this," he said. "Because this was her dream. She was living her dream."
Death devastates those at big cat sanctuary
When she was 6 or 7, Dianna Hanson was convinced she'd someday go to Siberia to study Siberian snow tigers. Her obsession with them and, eventually, other big cats never left her, according to her father.
Her first hands-on experience with such animals came while a student at Western Washington University in Bellingham, where she helped take care of lions and tigers owned by a family there.
The six-month internship at Cat Haven was her big break -- her ticket, she hoped, to getting a full-time job at a zoo. Paul Hanson said that his daughter was impressed with everything about what she considered "a very safe, well-run place" where the animals got far more room to roam than at most zoos.
"She was just really impressed with the way it was laid out and organized," he said. "There was never any question of safety in her mind or any mismanagement."
Cat Haven's founder, Dale Anderson, said the facility has been "incident-free" since it opened in 1998.
And Dianna Hanson quickly became part of the "family," lightening the load and brightening the mood wherever she went, recalled the non-profit's president, Wendy Debbas. She gave the animals songs -- for a jaguar named Samba it was "La Samba," to the tune of "La Bamba," while another named Rose had "Kissed by a Rose."
"She made instant friendships with everybody up here," Debbas said. "Everybody loved her."
They don't -- at least now, at least publicly -- have an explanation as to what happened to her.
The Fresno County Sheriff's Office said that when the lion attacked, another employee at the sanctuary tried to distract him away from Hanson and move him into another enclosure.
"But all attempts failed," the office said.
A sheriff's deputy shot and killed the animal to reach Hanson and give her medical assistance. However, it was too late.
"Our whole staff is ... it's just, it's devastating," Anderson said Thursday, choking back tears.
'They are wild animals, end of story'
The autopsy finding on Hanson will be reviewed by a veterinarian at the California Department of Fish and Wildlife, which is conducting the necropsy on the lion.
"Fish and Wildlife has trained our officers in California to recognize a lion kill due to our abundance of mountain lions," Hadden said, noting that the coordination between the two camps follows a protocol set up in case of a mountain lion attack.
"We never in our wildest imagination thought it would be an African lion."
Fatal lion maulings are rare in the United States, though not unprecedented.
Twenty people, including five children, have been killed by big cats in the United States in the past 21 years, according to figures kept by Big Cat Rescue, a nonprofit cat sanctuary in Tampa, Florida.
Another 246 people were mauled in the United States during that same time period, 1990 to 2011, the group said.
The attacking lion, Cous Cous, was one of Dianna Hanson's favorites, according to her father. The lion was also a celebrity of sorts, having appeared on Ellen DeGeneres' television
That said, noted animal expert Jack Hanna said any big cat can be unpredictable in the way it reacts to what it sees or hears.
"They are wild animals, end of story," he said. "No matter what anyone says, they are wild animals."
CNN's Ted Rowlands reported from California, Cristy Lenz reported from Atlanta, and Greg Botelho wrote the story. CNN's Steve Almasy contributed to this report.