A deadly rampage by a 67-year-old suspect in Northern California was likely an act of workplace violence, authorities said on Tuesday, offering fresh details about the second in back-to-back mass shootings that killed 18 people and horrified the nation.
In two separate shootings within three days, 11 people were killed at a Los Angeles-area dance hall and seven others were murdered at two farms in the seaside town of Half Moon Bay near San Francisco.
Authorities said they still were trying to determine motives for both shootings.
Preliminary evidence indicated that the massacre in Half Moon Bay was a case of workplace violence and that the gunman had used a legally-owned weapon. In the Southern California shootings, officials have declined to make any statement regarding a possible motive.
The suspects in both attacks are men of retirement age, much older than typical perpetrators of deadly mass shootings that have become routine in the United States.
On Monday, a gunman in Half Moon Bay opened fire on employees at Mountain Mushroom Farm, where he had previously worked, and Concord Farms, about a mile away.
The suspect, 67-year-old Chunli Zhao, was taken into custody later after he was found sitting in his vehicle, parked outside a sheriff's station. Authorities said they believe he had come to surrender.
He killed seven and wounded one, and all of his victims were Hispanic and Asian Americans, San Mateo County Sheriff Christina Corpus told reporters on Tuesday.
