"Very sad. Very, very sad," LaJoye-Young said to reporters at the scene.
"It's been very difficult for our investigators and I'm sure it is for the community as well," she said.
"Certainly, a horrific thing to be called to and my heart goes out to the families involved here and we're certainly going to do everything we can to bring this to resolution."
The sheriff also said authorities do not believe there's any threat to the public, WILX reported.
WOOD reported that investigators think the children were killed at a different location than the home where their bodies were found.
Authorities told reporters there’s a second crime scene that they haven’t found yet.
While the sheriff would not confirm the deaths were a murder-suicide, family members told reporters that Moore had a history of mental illness and that they believe she killed the children, then herself, according to WOOD.