Detectives located the suspect and the children by tracking signals from both his cellphone and his slain girlfriend’s, which had gone missing, Kings County Sheriff David Robinson told reporters at a news conference on Thursday.

The Amber Alert included Los Angeles, Orange, San Diego and Riverside counties, with authorities saying the suspect may have fled to Mexico.

Authorities in Kings County issued an Amber Alert Wednesday for two young girls believed to have been abducted by their father after the girls' mother was found fatally shot at a residence.