Last week Bubba attacked 5-year-old Katya Todesco; he bit her on the face and neck. Katya died a few days later at Children's Hospital of Los Angeles.
Bubba is now in quarantine.
Officials say Katya was at a neighbor's house on Appleton Road when the attack occurred. She went to the back yard and may have stumbled onto the dog.
"The child, kind of backing up, tripped over the dog, or somehow made contact with the dog. The dog was just at rest ... and, just, whirled around because the dog was startled and probably hurt and just attacked," said Kathy Jenks, Ventura Animal Regulation.
The family didn't want to talk about the incident on Tuesday. The mother who was there when Katya was attacked spoke to the Ventura County Star. She said, "It was a horrible attack. With my own hands I was pulling the dog's jaw."
"That's sad. They should do away with those dogs. I really don't like them," said a member of the Garcia family, who lives down the street from the Todesco home.
They family says they worry when they see dogs in the neighborhood and are being a little extra careful with the kids.
"I see them running around and sometimes they'll come up to my yard and I just close the door. I don't even want to come out," said a Garcia family member.
"There's a lot of pit bulls on the street that I see ... I mean, and that scares me now. I don't even want to let them walk around because they walk around the neighborhood too," said neighbor Randy Garcia.
Todesco's parents donated Katya's organs. So on Tuesday, a flag from "Donate for Life" flew from the family's garage. Donate for Life is an organization that encourages organ donations.
Simi Valley police say they are investigating the incident, but so far it appears to be an accident. Animal regulation officials say this is an unfortunate warning that any dog can be dangerous.
"There is no dog -- and I don't care if it is a Chihuahua, an Irish wolf hound and everything in between -- there is no dog that is safe to be alone, without an adult present, with a child under the age of about 10, depending on the size of the child," said Jenks.
Authorities said the 35-pound male pit bull is being held in quarantine and will likely be euthanized.