HONG KONG – Police in Shanghai were deployed over the weekend to crack down on Halloween celebrations amid fears that revelers would once again show up in costumes considered politically sensitive.

Last year, huge crowds gathered to celebrate Halloween around Julu Road in the heart of China's financial capital. It was the first Halloween since China emerged from three years of pandemic isolation, and some people dressed up in hazmat suits and other costumes related to Covid and other social and economic issues.

Others wore costumes made from blank sheets of paper, a nod to rare mass demonstrations in late 2022 in Shanghai and other Chinese cities against the country's “zero Covid” restrictions, which included a strict two-month lockdown in Shanghai. Chinese authorities responded by lifting nationwide restrictions all at once, unleashing Covid-19 on a population that had previously had little exposure to it.

In the days leading up to Halloween on Thursday, Shanghai police set up makeshift barriers on Julu and surrounding streets to discourage partygoers from gathering.

Video shared on social media and geolocated by NBC News shows dozens of police officers crossing a street near Zhongshan Park, where Halloween revelers have been gathering in recent days. In another video, a man dressed as Buddha was taken away by two police officers near the same location.

“I went for a walk this evening and there were police everywhere. My 6-year-old wore a hat with a pirate emblem and they even asked him to take it off,” read a comment from a Shanghai resident on Chinese social media platform Weibo on Sunday.

There was no official announcement of an outright ban or clear restriction on Halloween activities from Shanghai authorities, but local businesses reported receiving notices. A business owner who runs bars in Shanghai's Jing An district said on Chinese social media that police had told him not to hold parties or wear “bizarre clothes” on Halloween.

The bar owner could not immediately be reached for further details. The police in Jing An could not be reached for comment. The Shanghai Information Office did not respond to a request for comment.

Halloween-related activities appeared to go ahead as planned at Shanghai Disneyland and another theme park, Happy Valley. But Zhongshan Park, where videos circulating online showed revelers gathering in recent days, said on Saturday it would close from Sunday afternoon, without giving a reason or saying when it would reopen.

Shanghai's Jinjiang Action Park said on Sunday that it would not allow anyone in costumes during its month-long “Magic Fantasy Festival,” which appears to celebrate the Halloween season, to ensure a “safe and orderly experience for visitors.” The park had encouraged visitors to wear “colorful” makeup and “exquisite, unique” clothing for the event.

As Reuters reported, news of the crackdown was a trending topic on Weibo on Saturday. But on Monday, online censorship appeared to have suppressed discussion.

“It is a waste of resources. “If so much effort is being put into it, it should be about making sure people are safe and having fun, not about restricting or suppressing them,” reads one of the few remaining comments.