Half Moon Bay is about 30 miles (50 km) south of San Francisco.

Deputies responding to a call found four people dead and a fifth victim wounded at the first location in Half Moon Bay, then found three more dead at another place nearby, Sheriff Christina Corpus told a news conference.

One of the locations was a mushroom farm, the San Francisco Chronicle said.

Video on ABC 7 from the Bay Area showed the arrest as two men in plainclothes and one uniformed deputy, guns drawn, ordered the man out of his car. The suspect came out, was thrown to the ground and searched for weapons. Multiple uniformed officers quickly arrived on the scene with long guns.

A gun was found in his car, Corpus said.

A woman who witnessed the arrest told reporters she had gone to the sheriff's department to get more information as she was involved in agriculture and concerned about the well-being of the farm workers, who were already under stress because of recent flooding in the area.

"I came down here to find out what I could about the situation and why this happened and I hadn't expected to get quite that close to it," Kati McHugh told reporters on the scene. "It was a little too close for my comfort."

The latest mass shooting took place just two days after another in which 11 people were killed in the city of Monterey Park in Los Angeles County, about 400 miles (640 km) to the south.

Source: VNE