Cops said Tuesday that California’s latest mass shooting, which left seven people dead in Half Moon Bay on Monday evening, was carried out by a disgruntled employee who gunned down his co-workers. Zhao Chunli, 66, was arrested Monday night after allegedly slaughtering his co-workers in two locations earlier in the evening, San Mateo County Sheriff Christina Corpus said at a Tuesday press conference. The shooting came just days after 11 people were gunned down in a majority Asian neighborhood near Los Angeles. The victims of Monday’s shooting were all Hispanic or Asian, Corpus said, and were co-workers of Zhao’s at the Mountain Mushroom Farm in Half Moon Bay—a small town of 12,000 just south of San Francisco. Corpus said Zhao used a semi-automatic handgun to carry out the massacre by himself. She said he was cooperating with investigators on Tuesday.