Hong Kong police fired water cannon, rubber bullets and round after round of tear gas at petrol-bomb and brick-throwing protesters on Sunday in some of the most widespread violence in more than three months of anti-government unrest.

Running battles in the Causeway Bay shopping district, Wan Chai bar area and the Admiralty district of central government offices followed a night of showdowns with the police in the Chinese-ruled city after a peaceful pro-democracy rally turned ugly on the streets outside.

More protests are planned in the run-up to China’s October 1 National Day, marking the 70th anniversary of the founding of the People’s Republic.

The police also fired tear gas from the roof of the Legislative Council building, which activists trashed and daubed with graffiti weeks ago.

Protesters, many of them wearing their trademark black with face masks, took cover from the tear gas behind umbrellas and held their ground on Sunday, some throwing tear gas canisters back at the police as a helicopter flew overhead.

They built barricades with trolleys and trash cans and other debris. One threw a petrol bomb at the police in the Wan Chai Metro station.

At least one petrol bomb landed in the grounds of central government offices where several windows were smashed. The police, who traditionally raise placards warning of retaliation before firing tear gas or water cannon, made several arrests, grappling people to the tarmac. There were no immediate reports of serious injuries.

The government said the city’s leader, Carrie Lam, would on Monday leave for Beijing for China’s National Day, despite her having sent out invitations for celebrations at home.

Some shops closed ahead of expected demonstrations, while the MTR Metro service shut stations, a move that has made it a target of violence in the past.

Protesters shouted anti-China slogans and called for their “five demands, not one less” of the government, including universal suffrage and the dropping of all charges against their arrested colleagues.

About 200 China supporters dressed in red T-shirts gathered on top of Victoria Peak, overlooking the harbour, around midday. They sang the Chinese national anthem and chanted “I love China”.