TORRANCE, Calif. (AP) — Detectives say there were several knives recovered at a bloody scene in Southern California where a mother has been arrested in the killing of her three young daughters.

But Los Angeles County Sheriff's Lt. Dave Coleman says it's not clear how the three girls, who ranged in age from 3 years to 2 months old, were killed.

Detectives are completing their investigation and clearing out of the scene on Wednesday morning, more than 12 hours after the children's grandmother called them to the home in the unincorporated area near Torrance.

Neighbors say the mother was taken from the scene into an ambulance covered in blood and naked except for a blanket.