In the wake of violent clashes in Hong Kong on Sunday, during which a live gunshot was fired for the first time since protests began in early June, Chinese state media used its harshest rhetoric yet to condemn the unrest and warned that Beijing could soon intervene.

The 12th straight weekend of protests in the semiautonomous enclave took a dangerous turn when police deployed water cannons and one officer fired a gun into the air to disperse protesters, who hurled bricks and petrol bombs at officers in the New Territories district of Tsuen Wan.

The Hong Kong government confirmed that six police officers drew their pistols to fend off protesters attacking them, with one of the officers firing a warning shot into the air. At a press conference on Monday, the police force justified the warning shot, saying their “officers’ lives were in great danger” and that their use of force was “necessary and reasonable.” The use of live ammunition is extremely rare in Hong Kong.

Following the clashes, China’s state-run Xinhua News Agency published a commentary asserting that Beijing has the authority and the responsibility to step in and quell the unrest. “If riots happen, the central government has to intervene,” Xinhua said, drawing on historic comments from China’s paramount leader Deng Xiaoping.

The commentary also called the protests a “color revolution” aimed at overturning the government. Chinese government officials have in previous weeks said that the protests have the characteristics of a “color revolution,” a reference to pro-democratic uprisings in former Soviet states and the Balkans throughout the early 2000s.

This weekend’s return to violence followed a peaceful march the previous Sunday which organizers say 1.7 million people attended. On Friday, protesters formed a human chain across the city in a nod to a 1989 protest in the Baltic states against Soviet Union rule.

Read More: A Brief History of Protest in Post-Handover Hong Kong

Police said that 21 officers were injured and 86 people were arrested over the weekend, including a 12-year-old child.

Protests began in early June as a series of peaceful marches against a now-suspended bill that would have for the first time allowed Beijing to extradite criminal suspects to the mainland to face trial under the Communist Party-controlled court system. But the movement has morphed into a wider antigovernment campaign, with some protesters calling for full democracy in the former British colony.

Protests have become a common occurrence in the city, and have frequently descended into violent clashes with police, who have been criticized for their use of force. In recent weeks, demonstrators have shut down the city’s subway trains and the international airport with organized rallies.

Fears have risen in recent weeks that Beijing could intervene in the lead-up to its National Day celebration on Oct. 1, marking the 70th anniversary of the People’s Republic of China. The People’s Liberation Army has a permanent presence in Hong Kong, while there have been reports of China’s paramilitary police force amassing in the nearby city of Shenzhen.

Write to Amy Gunia at amy.gunia@time.com.