Seven people were killed in two related shootings at agricultural facilities in California, marking the state’s third mass killing in eight days.

Officers arrested a suspect, 67-year-old Chunli Zhao, after they found him in his car in the parking lot of a sheriff’s substation, San Mateo County Sheriff Christina Corpus said.

Four people were found dead and a fifth injured from gunshot wounds at a farm on the outskirts of Half Moon Bay, the sheriff’s office said.

Officers found three other people killed at another location several miles away.

Corpus said officials believe Zhao is a worker at one of the facilities and that the victims were workers as well. Some workers at one facility lived on the premises and children may have witnessed the shooting, she said.

Law enforcement officials investigate a shooting
Law enforcement officials investigate following a mass shooting on January 23, 2023 in Half Moon Bay, California.
Justin Sullivan/Getty images

Officials hadn’t determined a motive for the shooting, she said.

The incident is the sixth mass killing that the U.S. has seen in less than three weeks, according to the Gun Violence Archive. The database defines a mass killing as four or more people killed in a single incident not including the shooter.

Three have taken place in California since January 16, when a teenage mother and her baby were among six people killed in a shooting at a home in California’s Central Valley.

Then Saturday’s attack at a dance hall in Monterey Park left 11 people dead during Lunar New Year celebrations.

California Gov. Gavin Newsom tweeted that he was “at the hospital meeting with victims of a mass shooting when I get pulled away to be briefed about another shooting. This time in Half Moon Bay. Tragedy upon tragedy.”

This is a breaking news story and will be updated.