NINGBO, China (AP) ― Protests over pollution fears resumed Sunday in an eastern Chinese city where thousands of residents had clashed with police a day earlier while demonstrating against the proposed expansion of a petrochemical factory.

Several hundred citizens of Ningbo, which is in Zhejiang province, set off from a city square and headed for the offices of the municipal government on Sunday morning. Hundreds were stopped at the gate of the offices by a circle of uniformed police. They shouted for the release of people they believed had been detained by police a day earlier, for the protection of Ningbo and for the city’s mayor to come out.

“We can only depend on ourselves now, we can’t count on the government to think about us,” said one protester, a 40-year-old woman surnamed Jing.

On Saturday, residents reported that protests turned violent after authorities used tear gas and arrested participants. Authorities said “a few” people disrupted public order.

Such protests are exactly what the Chinese leadership does not want coming on the eve of a once-a-decade transition of power, with stability being paramount.

The demonstrations are a reminder to the incoming generation of leaders that they face a public increasingly unwilling to accept the environmental and health hazards as an inevitable consequence of breakneck, unbridled economic growth.

On Sunday, there was a noticeable security presence at the city square, which is located in a shopping district. Several dozen uniformed police officers stood around and some walked with protesters, appearing to allow them to express their grievances without taking action.

The mood was fairly cheerful, with children among those who marched and parents carrying their babies in their arms.

Some protesters wore face masks and shouted slogans including “Protect Ningbo” and “Return my health” while pumping their fists in the air. Cars were forced to stop as a long stretch of people marched along roads.

“We have to do this for our future and our family’s future,” said Jing, the protester, as she pointed to the smoggy air. “The sky was so clear when I was a child. Look at it now.”

Another protester, Yu Yibing, said he wanted the factory to be closed, not expanded, and his 7-year-old son to grow up in a clean environment.

“As the common people, we need to live in a green environment. This is a reasonable request,” said Yu, 38. “But the government only puts out some statement and refuses to see us and also suppresses us. I don’t know how else we can express our views.”

The Zhenhai district government, which comes under the Ningbo government, said Ningbo’s Communist Party chief, Wang Huizhong, and mayor, Liu Qi, had held discussions with local residents Saturday night.

A statement posted on the district government’s website Sunday said that the opinions and advice of the people who attended “are very helpful” to the party committee and municipal government’s decision-making and that the expansion project was “at an early stage.”