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.

Two girls who authorities say were abducted by their father after he allegedly killed their mother, were found safe and the suspect taken into custody.