HONG KONG (Reuters) - Hong Kong’s businesses and metro stations reopened as usual on Monday after a chaotic Sunday when police fired water cannon, tear gas and rubber bullets at protesters who blocked roads and threw petrol bombs outside government headquarters.

FILE PHOTO: A general view of Victoria Harbour and downtown skyline is seen from the Peak in Hong Kong, China August 4, 2017. REUTERS/Bobby Yip

On Sunday what began as a mostly peaceful protest earlier in the day spiraled into violence in some of the Chinese territory’s busiest shopping and tourist districts.

Thousands of anti-government protesters, many clad in black masks, caps and shades to obscure their identity, raced through the streets, engaging in cat-and-mouse tactics with police, setting street fires and blocking roads in the heart of Hong Kong where many key business districts are located.

The demonstrations are the latest in nearly four months of sometimes violent protests. Protesters are furious over what they see as creeping interference by Beijing in Hong Kong’s affairs despite promises by Beijing to grant the city wide-ranging autonomy and freedoms denied in mainland China.

Dozens of university students rallied peacefully on Monday afternoon urging authorities to listen to public demands. Dressed in black, some of them donning face masks, students sang “Glory to Hong Kong” a song that has become a rallying cry for more democratic freedoms in the semi-autonomous Chinese hub.

At Baptist University hundreds of students also marched to demand the university’s management offer support to a student reporter arrested on Sunday.

The initial trigger for the protests was a contentious extradition bill, now withdrawn, that would have allowed people to be sent from Hong Kong to mainland China for trial.

The protests have since broadened into other demands including universal suffrage and an independent inquiry into allegations of excessive force by the police.

Hong Kong, a former British colony, returned to China in 1997 under a “one country, two systems” formula that guarantees freedoms not enjoyed on the mainland - including a much-cherished independent legal system.

89 ARRESTS IN WEEKEND VIOLENCE

Kung Lui, a third-year university student majoring in sociology, said the protests would continue until all five demands were met. “The protests have revealed lots of social problems and proved that democracy and freedom are the core values of Hong Kong people.”

Police on Monday said 89 people were arrested over the weekend after “radical protesters” attacked two police officers on Sunday evening, hurling petrol bombs, bricks, and threatening the safety of the officers.

Nearly 1,500 people have been arrested since the protests started in June.

Authorities moved quickly to douse the fires and police fired volleys of tear gas to disperse them, including in the bustling shopping and tourist district of Causeway Bay.

At least 18 people were injured, three of them seriously, during Sunday’s violence, according to the Hospital Authority.

The protests have weighed on the city’s economy as it faces its first recession in a decade, with tourist arrivals plunging 40 percent in August amid some disruptions at the city’s international airport.

By Sunday evening, the running battles between anti-government protesters and police had evolved into street brawls between rival groups in the districts of Fortress Hill and North Point further east on Hong Kong island. There, men in white T-shirts - believed to be pro-Beijing supporters and some wielding hammers, rods and knives - clashed with anti-government activists.

On a street close to North Point, home to a large pro-Beijing community, a Reuters witness saw one man in a white T-shirt sprawled on the ground with head wounds.

Hong Kong media reported that groups of pro-Beijing supporters had attacked journalists.

Police eventually intervened and sealed off some roads to try to restore order, and they were seen taking away several men and women from an office run by a pro-Beijing association.

Democratic lawmaker Ted Hui was arrested for allegedly obstructing police, according to his Democratic Party’s Facebook page, as he tried to mediate on the streets in North Point.