Hong Kong police on Sunday toughened their crowd control measures, pushing back forcefully with tear gas and water cannons against pro-democracy protesters as tensions continue to spike ahead of China’s National Day celebrations on Tuesday.

Running street battles with the riot police began in the early afternoon after thousands of demonstrators descended on Hong Kong’s normally crowded central shopping district of Causeway Bay for an unauthorised march.

Chaos and violence broke out as protests against Beijing’s rule gripped the city for the 17th consecutive weekend, in what began as a movement against a controversial mainland extradition bill but has now morphed into a wider cry for democracy and universal suffrage.

The civil unrest has intensified in recent days as protesters become more determined to amplify their message ahead of the Chinese Communist Party’s highly choreographed events to mark the 70th anniversary of the People’s Republic of China.

Although Sunday’s march drew thousands of peaceful participants, it quickly took an aggressive turn as police stopped and searched a number of young people dressed in black and fired tear gas before the planned 3pm start time, sending panicked shoppers and protesters fleeing.