DUNLAP, California (AP) - A California animal sanctuary where an African lion killed a 24-year-old intern reopened to the public Sunday with the support of the victim's family.

Cat Haven, a private zoo run by the nonprofit Project Survival, observed a moment of silence at noon for Dianna Hanson, who was fatally attacked by the 250kg male lion Wednesday.

Cat Haven founder Dale Anderson said the park was returning to normal operations so the staff could focus on taking care of its remaining 29 wild cats, but "we continue to mourn the loss of two family members."

"Dianna would want the work that we are doing to continue and we are re-opening to the public with consent from Dianna's parents," Anderson said at Sunday's news conference. "Her passion for working with these animals was contagious." Investigators believe the lion, known as Cous Cous, lifted the door of a partially closed feeding cage with its paw and attacked Hanson as she cleaned a larger enclosure area, according to Fresno County Coroner David Haden.

Hanson, who had been working as a Cat Haven volunteer for two months, died immediately from a broken neck, according to the coroner's report.

A sheriff's deputy fatally shot the 5-year-old lion after it couldn't be coaxed away from Hanson's body.

Fresno County Sheriff Margaret Mims did not provide many new details about the investigation at Sunday's news conference, but said the gate that was supposed to contain the lion was not completely closed.

"We believe this was an accident, an error," Mims said, according to the Fresno Bee.

Hanson's relatives say they also believe her death was an accident and that safety protocols were followed at Cat Haven, a 40ha park in the Sierra foothills about 65km east of Fresno.

Wendy Debbas, president of Project Survival, read a letter Sunday from Donna Anderson, the victim's mother, who said she supports the decision to reopen Cat Haven.

"I am living every mother's worst nightmare in losing a cherished child," Ms Anderson said in the letter. "It is my desire that they continue their mission in support of saving my daughter's beloved creatures." Ms Hanson's family announced on Friday that a fund has been set up in her memory and urged people to donate to the wildlife organisations she loved, including Cat Haven.

"Her legacy will live on through the support of conservancies such as Project Survival's Cat Haven," Ms Anderson said.