When the deputy entered the home, she found the bodies of two young girls, their mother and grandmother.
The deputy was called to the home to perform a welfare check. When she heard the shots fired, she took cover, thinking the shots were aimed at her.
Seconds before the shots were fired that killed 4-year-old Catherine Fontaine, her 2-year-old sister, Julia, their mother, Elizabeth Fontaine, and their grandmother, Bonnie Hoult, an Orange County Sheriff's deputy was trying to get in the door of the San Clemente home.
"She did see the grandmother, Bonnie, with the 4-year-old child holding her hand," said Orange County Sheriff's Spokesman Jim Amormino. "Once the grandmother saw the deputy, she began walking briskly toward the open garage door. The deputy tried to catch up with her. She put her foot in the door but the grandmother was able to slam the door, then lock it."
The deputy then heard four gunshots.
Authorities were first called to the house by Kevin Herbert, who lives at the home, and had allowed the four to stay there while they were visiting.
Herbert didn't want to talk about what happened on camera. Authorities say he didn't see a gun, but he was worried enough to grab his own family and leave.
Seven minutes later, the deputy showed up at the house to do the welfare check.
"I don't think anything could have been done differently," said Amormino. "It wasn't a case where a gun was seen and it was imminent. There's no reasonable cause to use force."
Authorities are waiting for further test results to determine who fired the gun. It was registered to the 67-year-old Hoult.
Hoult's daughter, 38-year-old Elizabeth, filed for divorce from her husband, Jason Fontaine, last year. Elizabeth accused him of molesting their oldest daughter. Charges were never filed. Jason's attorney says experts found the allegations were not true.
A month ago, Elizabeth, her kids and mother moved to Texas, where she tried to re-open the case, but a California judge ordered her back to Orange County and planned to give temporary custody of the children to Jason's sister while the case was sorted out.
Elizabeth was supposed to return to court with children Monday, the same day as the murder-suicide.
Authorities are waiting on fingerprints and DNA test results, which could take one to two weeks.