The police chief in Fresno, California said Tuesday that terrorism remains a possible motive in the series of shootings by an African-American man that killed four people since last week. Thirty-nine-year-old Kori Ali Muhammad first murdered an unarmed security guard at a motel on Thursday and then killed three others on Tuesday before he was captured. All of his victims were white. The gunman shouted "allahu akbar" while carrying out Tuesday's attack. The police chief said it is too early in the investigation to rule out terror as the motivation for the rampage.