Rioting carries a prison term of up to 10 years.

As news of the charges spread, hundreds of people dressed in black, the color of the protest movement, gathered around Kwai Chung Police Station, where the suspects were being held. The police told the crowds to disperse and used pepper spray against some demonstrators.

“I feel very unhappy,” said Jax Liu, a 21-year-old computer technician who went to the police station to support the arrested protesters. “I can’t accept that the one making the mistake was the government, but we are those who get punished.”

Around 11 p.m., a small number of officers came out of the station to confront protesters, including one police officer holding a shotgun that he pointed at some of those gathered, but he did not fire. The gun did not have the distinct orange color of those the police have been using to fire rubber bullets, raising fears they were deploying more lethal weapons.

A police spokeswoman said she had no immediate information about the incident.

The Hong Kong Journalists Association said an officer charged a reporter outside the station, knocking him over with a shield, and chased another with a baton. Several reporters were also hit with pepper spray.