Officers arrived at the scene and found five people dead, including the gunman, whose identity has not yet been released.
The 39-year-old’s estranged wife had a restraining order against him, and only supervised visits with their kids were allowed, Sergeant Rod Grassmann said during a press conference.
The incident is being referred to as an act of domestic violence, according to Grassmann.
Following the incident, California Governor, Gavin Newsom, expressed his condolences on Twitter.
“Another senseless act of gun violence in America — this time in our backyard. In a church with kids inside. Absolutely devastating,” he tweeted. “Our hearts go out to the victims, their families and their communities. We are working closely with local law enforcement.”
As of now, police report that a motive is unknown and the shooting is under investigation by several departments.
“When something big like this happens, everyone comes to help us out,” Grassmann told reporters. “Everybody has come out of their own jurisdiction to come to do what they can to help out not knowing how big this scene would be or how long it would go on.”