A volunteer mauled by a lion Wednesday at an animal sanctuary east of Fresno died instantly of a broken neck, apparently from the swipe of a paw, Fresno County Coroner Dr. David Hadden said Thursday.

Hadden said an autopsy revealed that Dianna Hanson, 24, suffered the broken neck first, so she didn't suffer as the 5-year-old African lion continued to bite and claw and toss her body around.

"It was a merciful way to go," said Hadden.

Hanson had been an intern at Cat Haven, operated by the nonprofit Project Survival in the town of Dunlap, for two months when she was attacked by the 450-pound lion in the animal's enclosure.

When the lion would not allow anyone near Hanson's body, a Fresno County sheriff's deputy fired several shotgun rounds and killed it.

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The Sheriff's Office is investigating the fatal mauling, which the Coroner's Office has listed as an accident.

Thursday, Assistant Sheriff Tom Gattie said no new information would be released until an investigation is completed. Gattie gave no timeline.

Dale Anderson, founder of the Cat Haven, also offered few details of what happened, saying that the nonprofit wildlife sanctuary was working with the sheriff's investigation. But he said the facility had never had an incident involving its animals since it was founded in the 1990s.

Anderson said he and other staff members took a cheetah to two Fresno schools Wednesday morning, while Hanson and the sanctuary's head keeper, who was not identified, did their normal routine of feeding the animals.

According to the sanctuary's guidelines, caretakers should never be inside with the big cats.

The 450-pound lion, named Cous Cous, lived with a female lion named Pele, Anderson said. The lions' enclosure lies on the side of a hill. At the top of the enclosure is a small, enclosed shelter that serves as the feeding area, Anderson said. The shelter has two cages with pull-up gates that separate the smaller shelter from the larger, fenced enclosure.

Hadden, the coroner, said investigators told him that after Hanson fed the lions, she began cleaning the larger fenced enclosure.

Gallery: Fatal lion attack at Cat Haven animal sanctuary

Hadden said the gate of the small shelter was either left open or Cous Cous used a paw to open it. Hanson was on her cell phone talking with a co-worker when the lion attacked, he said.

The co-worker became concerned when the conversation ended abruptly and Hanson failed to call back, the coroner said. The co-worker then called authorities when she went to check on Hanson. A sheriff's deputy shot Cous Cous after he couldn't be coaxed away from Hanson's body.

Hanson was pronounced dead at the scene.

Emotions still raw

On Thursday, Anderson and Wendy Debbas, president of the sanctuary's nonprofit board, nearly cried as they addressed a large gathering of reporters who stood at the bottom of the sanctuary's long, winding driveway off Kings Canyon Road.

"We lost a dear friend in Dianna," Anderson said.

"Dianna was part of our family," Debbas said. "She made instant friendships. Everybody loved her."

Anderson said the death of the lion, Cous Cous, was also difficult. "He was a great friend," he said.

Anderson said Hanson had signed up for a six-month internship starting in January. Hanson showed a carefree spirit and loved to make up songs about each big cat. For example, for a jaguar named Samba, she sang a tune similar to "La Bamba."