TUCSON, Ariz. (AP) — Tucson police are investigating the killing of a 28-year-old woman who was found with severely injured and who died while her three children were in the apartment.

Police say they haven’t arrested anyone in the death of Monique Leon on Thursday.

They said Leon’s boyfriend called 911 after returning home from work. There were no signs of a break-in.

The three children were unharmed.