She said that the police had warned civilians to stay away. “Under chaotic situations, it is indeed hard to determine whether someone is a real journalist, a protester or a violent person,” she said.

The violence in Prince Edward Station began during a dispute between protesters and some older men who were insulting them. One of the men swung a hammer at the protesters, who threw water bottles and umbrellas and later appeared to set off fire extinguishers in the car. After the clashes, the subway system suspended service across much of Hong Kong. Three stations remained closed on Sunday.

The subway operator, MTR, has been a target of vandalism since it began suspending service last month to stations in places near where protests are planned. It continued that pattern on Saturday, stopping service at Sai Ying Pun Station, near the Chinese government liaison office, a site of some protests.

In the wake of the clashes, Chinese news outlets run by the Communist Party urged the Hong Kong government to take tough steps against the protesters and cited experts urging Carrie Lam, the chief executive of the city, to invoke emergency powers. An online outlet controlled by the Communist Party’s law-and-order committee said the Hong Kong protesters were using “terrorist methods.”

“The chaos in Hong Kong cannot go on!” a front-page editorial in the overseas edition of People’s Daily, the party’s main newspaper, said on Sunday. “At this crucial moment, the government of the special administrative region must have the courage and adeptness to apply every legal means to halt the violence and chaos, acting resolutely to detain and arrest violent lawbreakers, applying the law strictly to punish criminals, and swiftly restoring social order.”

An online report from China’s main television broadcaster, CCTV, said that Mrs. Lam should invoke emergency powers under a colonial-era ordinance to extinguish the violent protests. That step could empower the Hong Kong government to ban demonstrators from wearing masks, speed up arrests and censor “harmful media,” the report said.