Chief Secretary Matthew Cheung, the city’s No. 2 official, said that police would arrest those who engaged in illegal activities after protesters disrupted traffic to the airport, hurled petrol bombs at cops and set fire to a massive roadblock in the city center. Demonstrators, by contrast, accused the police of indiscriminately beating civilians in a subway station on Saturday night.

“Stopping the violence is the top priority,” Cheung told reporters on Monday alongside other top officials from Chief Executive Carrie Lam’s administration. “Law and order must be restored ASAP, without further ado. No nonsense.”

His colleague, Security Secretary John Lee, said the level of violence was getting worse: “Radical protesters disregarded the law, and their illegal behavior and violence continued to spread and escalate, showing signs of terror.” So far, city authorities have resisted describing the protests using the word “terror,” a term invoked by mainland officials.

The city’s 13th straight weekend of unrest since early June showed no end in sight to the most serious challenge to Beijing’s control over the former colony since its return to Chinese rule in 1997. The demonstrations, which again disrupted the city’s busy international airport, spilled into Monday with students boycotting classes and calling for a general strike on the first day back to school.

The briefing on Monday showed that authorities were still considering a colonial-era emergency law that would grant the government sweeping powers to arrest, search properties, censor publications and shut down the Internet. Cheung declined to rule out using the so-called Emergency Regulations Ordinance, enacted by the British in 1922 and last used to quell violent riots in 1967, saying only that such powers would need to be “reasonable.”

As the work week began, riot cops were dispatched into the city’s subway stations to keep order amid plans to disrupt the morning commute, even though it ended up relatively smooth.