ORANGE, Calif. (AP) – Southern California police say the man who killed four people and wounded a fifth at an office complex knew all the victims either through business or personally. Orange police Lt. Jennifer Amat also revealed that the gunman had chained gates to the complex closed, forcing officers who responded Wednesday to engage him from outside. Police withheld the identities of the dead but said one was a 9-year-old boy. The others were a man and two women. The suspect was also wounded and hospitalized. Wednesday’s shooting happened in the city of Orange southeast of Los Angeles. California Gov. Gavin Newsom called the killings “horrifying and heartbreaking.” It was the nation’s third mass shooting in two weeks.