Authorities say a 56-year-old woman has died, a day after her 14-year-old daughter allegedly struck her in the head with a hammer or other blunt object.

Rebecca “Becky” D’Aoust died Monday. She worked as a counselor at a San Diego elementary school.

Her 14-year-old daughter was arrested following Sunday morning’s attack in the family’s Scripps Ranch home about 15 miles north of downtown San Diego. The girl is being held on suspicion of murder.

Officers called to the home found D’Aoust on the kitchen floor with a serious head injury.

Lt. Kevin Rooney said investigators still don’t know a motive for the attack and have not released the name of the 14-year-old because she is a minor.