San Mateo County Board of Supervisors President Dave Pine says four people were killed at the farm and three at the trucking business on the outskirts of Half Moon Bay, a city about 30 miles (48 kilometers) south of San Francisco.
It wasn’t immediately clear how the locations were connected.
California state Sen. Josh Becker, who represents the area, said people were killed in separate shootings. San Mateo County Supervisor David Canepa tweeted that one shooting happened at a mushroom farm.