MARTINEZ — The former operators of a Bay Area buffet restaurant chain that allegedly stole millions from low-wage workers were served with a whopping $6.1 million bill and sentenced to prison Friday.

Defendants Yu Chen, Feng Gu, and Rongdi Zheng were among eight defendants charged in December with wage theft and other labor code violations. Authorities say the three helped manage a Chinese buffet chain owned by a man named Brandon Quang that paid some workers less than $6 per hour, forced them to work 12-hour shifts with no overtime, and bused them to and from work, forcing them to stay in racially-segregated dorms.

Chen, Gu, and Zheng were each sentenced to 3½ years in prison Friday, and are required to pay $4.5 million to their workers, along with another $1.5 million to the state of California in back taxes. Another of the defendants, Shao Rong Zhang, pleaded no contest to a misdemeanor charge of enforcing a policy on behalf of her employer that employees not report minimum wage violations, and was sentenced to 120 days in jail.

In late May, prosecutors dropped the charges against Zhou Xian Chen, who was thought to be less involved. Quang, and defendants Guo Cai Feng and Lin Jiang, fled the area to avoid prosecution and are believed to be hiding out in China.

The buffet chain included Golden Dragon Buffet in Brentwood, New Dragon Buffet in San Leandro, Golden Wok Buffet in Roseville and Kokyo Sushi Buffet in Hayward. A state investigator, Donna Chen, began looking into the chain in 2013 and developed a rapport with some of the workers, who later testified at a grand jury hearing where the eight defendants were hit with a lengthy indictment.

Witnesses described being housed in overcrowded private residences around the Bay Area, which were segregated by race and gender. One said he slept in bunk beds in a garage with about a dozen others, and was required to work six days a week with no overtime. When a few complained about the poor working conditions, they were fired, evicted and threatened with deportation, according to witness statements.

Before handing down the sentence, Superior Court Judge Charles “Ben” Burch heard from a few workers, whose identities are protected in court records. One told the judge: “I will never be the same. … I want justice to be served so that this won’t happen to anyone else. This shouldn’t happen to anyone else.”