After a Deadly Blaze, a Surge of Defiance Against China’s Covid Policies

“We do not consider this a credible explanation,” the BBC said.

Crowds also congregated in Chengdu, a city in southwest China, video from Sunday showed, with some shouting, “We want freedom, we want democracy.” Others yelled, “Freedom of speech, freedom of the press!”

May Hu, who lives in southern Hunan Province, said she spent hours watching a livestream of the Shanghai protests on Instagram, which is blocked in China unless using software to surmount censorship barriers.

“Before, everyone only thought about how to escape this all,” said Ms. Hu, who is in her 20s. “After, many people’s thinking has changed to, ‘We need to go fight and win freedom.’”

Some participants in the previous night’s gathering in Shanghai expressed fear that the widespread public fury could ultimately draw an equally furious official response. A recent college graduate who requested that only his surname, Li, be used, said that after seeing the police pushing and detaining people on Saturday night, he was nervous about joining another demonstration.

“After speaking out, some spectators maybe will feel empowered — that you can’t mess around with the people — but what will the outcome be?” said Ding Tingting, an art curator who joined the mourning vigil in Shanghai but disapproved of the rowdy chants later that night.

On Sunday evening, residents gathered in the same area, some shouting, “Release them,” apparently after the police seized people in sometimes rough encounters, video shared with The Times showed. Officers hurried others along, preventing them settling in place for any potential protest.