Updated

The 66-year-old farmworker accused of killing seven people at two mushroom farms in Half Moon Bay, California, is believed to have carried out the shootings over a $100 repair bill for farm equipment, officials said Friday.

Chunli Zhao met with his supervisor about the bill on Monday, blaming his co-worker for the damage to a forklift that Zhao was driving when it collided with the co-worker’s bulldozer, San Mateo County District Attorney Steve Wagstaffe said. However, the supervisor insisted that Zhao pay the bill.

Zhao then allegedly shot and killed the supervisor, two co-workers and the wife of one of the victims at Terra Garden. A fifth co-worker was wounded. He then went to nearby Concord Farms, where he had worked previously, and fatally shot three former co-workers, authorities have said.

Wagstaffe said Zhao had long been disgruntled over other work-related disputes but that the repair bill may have "lit the candle" for the deadly shooting, FOX2 KTVU in the Bay Area reported.

HALF MOON BAY, CALIFORNIA, DEADLY FARM SHOOTINGS: WHO IS SUSPECT CHUNLI ZHAO?

Chunli Zhao appears for his arraignment

Chunli Zhao appears for his arraignment at San Mateo Superior Court in Redwood City, Calif., on Wednesday. (Shae Hammond/Bay Area News Group via AP, Pool)

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

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.

police investigating shooting on farm

Police investigate the scene of a mass shooting off Cabrillo Highway in Half Moon Bay, Calif., on Monday. (Karl Mondon/Bay Area News Group via AP)

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

ANOTHER CALIFORNIA SHOOTING LEAVES 3 DEAD, 4 INJURED IN RITZY LA NEIGHBORHOOD

Wagstaffe said that prosecutors requested no bail since Zhao is not a U.S. citizen and has "plenty of reason to run."

Chunli Zhao arraignment

Zhao, a farmworker accused of killing seven people in back-to-back shootings at two Northern California mushroom farms, was charged Wednesday with seven counts of murder and one of attempted murder. (Shae Hammond/Bay Area News Group via AP, Pool)

In addition to seven counts of murder, Zhao was charged with one count of attempted murder, firearm use enhancements and a count of special circumstance allegation of multiple murders, Wagstaffe said.

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Zhao is due to appear in court on Feb. 16.

Fox News’ Sarah Rumpf and the Associated Press contributed to this report.