Northern California shooting case of ‘workplace violence’, police say

Authorities say 67-year-old killed four and wounded one at a mushroom farm then killed three more at a trucking firm

An agricultural worker in northern California allegedly killed seven people as part of a workplace violence incident", the state's third deadly mass shooting in little more than a week.

Police are questioning 67-year-old Chunli Zhao, who they say shot dead four and wounded one more on Monday afternoon at a mushroom farm where he worked in Half Moon Bay, a coastal community 30 miles south of San Francisco.