SACRAMENTO, Calif.—A man shot and killed his three children and a fourth person before taking his own life on Monday in an outburst of gun violence that unfolded in a church near California’s capital, police said. Sacramento County Sheriff’s Department spokesperson Rod Grassmann told reporters near the scene that investigators were seeking clues to a motive for the bloodshed but believed the shooting stemmed from a domestic dispute. “This was not a random shooting,” Grassmann said, adding that the gunman and his victims “knew each other.” The shooting erupted at about 5 p.m. local time inside The Church in Sacramento, located in the Arden-Arcade community on the eastern edge of Sacramento’s city limits, Grassmann told reporters. A church employee on an upper floor of the church at the time told authorities he heard a single gunshot, followed by several more shots before he ran out of the building and called …