Gunman in Southern California mass shooting knew his victims

This undated photo provided by the Orange Police Department shows Aminadab Gaxiola Gonzalez, a 44-year-old Fullerton, Calif., man who is the suspect in a shooting that occurred inside a counseling business in Orange, Calif., on Wednesday, March 31, 2021. A child was among four people killed Wednesday in the shooting at a Southern California office building that left a fifth victim wounded and the gunman critically injured, police said. (Orange Police Department via AP)

ORANGE, Calif. — The gunman who killed four people and critically wounded a fifth at a Southern California office building knew all the victims and apparently before opening fire chained shut the gates to two entrances, delaying police from getting inside, authorities said Thursday.