SAN FRANCISCO (AP) — A farmworker charged with killing seven people at two Half Moon Bay mushroom farms reportedly told investigators he was spurred to carry out the shootings after his supervisor demanded he pay $100 to repair a forklift damaged at work.

San Mateo County District Attorney Steve Wagstaffe confirmed to the Bay Area News Group Friday that Chunli Zhao was enraged by the equipment bill, saying that a co-worker was to blame for the collision between his forklift and the co-worker’s bulldozer.

KNTV-TV, the NBC affiliate in the San Francisco Bay Area, was first to report the development.

Authorities say Zhao, 66, shot and killed four workers and wounded a fifth employee Monday at California Terra Garden. He then went to nearby Concord Farms, where he had worked previously, and fatally shot three former co-workers.

Zhao told KNTV-TV in a courthouse interview Thursday that he committed the shootings. He said he was bullied and worked long hours on the farms and his complaints were ignored, the station reported.

In this photo taken by a drone, a cluster of mobile homes is seen at the California Terra Garden, formerly Mountain Mushroom Farm in Half Moon Bay, Calif., Thursday, Jan. 26, 2023. A farmworker accused of killing seven people in shootings at two Northern California mushroom farms, including this one, has been charged with seven counts of murder. Prosecutors filed the charges Wednesday. A court appearance for 66-year-old Chunli Zhao was postponed until Feb. 16. (Santiago Mejia/San Francisco Chronicle via AP)

On Monday, Zhao vented to his supervisor about the bill, but the supervisor insisted he needed to pay. Zhao then allegedly shot the supervisor and the co-worker, the news outlets reported.

Speaking in Mandarin, Zhao told the television station from a county jail in Redwood City that he has been in the U.S. for 11 years and has a green card. He said he has a 40-year-old daughter in China and lived with his wife in Half Moon Bay.

People gather at a community vigil for the Half Moon Bay shootings earlier in the week in Half Moon Bay, Calif., Friday, Jan. 27, 2023. (Gabrielle Lurie/San Francisco Chronicle via AP)

The coroner’s office has named six of the victims: Zhishen Liu, 73, of San Francisco; Marciano Martinez Jimenez, 50, of Moss Beach, California; Aixiang Zhang, 74, of San Francisco; Qizhong Cheng, 66, of Half Moon Bay; Jingzhi Lu, 64, of Half Moon Bay; and Yetao Bing, 43, whose hometown was unknown.

The charging documents identified Jose Romero Perez as the other person killed and Pedro Romero Perez as the eighth victim, who survived.