Petrol bombs were thrown inside a Hong Kong metro station on Saturday but no one was injured, the government said, as pro-democracy protesters again took to the streets angry at what they believe is Beijing’s tightening grip on the city.

Axar.az reports citing Reuters that The Kowloon Tong station was seriously damaged in the attack, the government said in a statement.

Hundreds of protesters, many young and wearing face masks, were marching in Kowloon at the time and were headed to a district near the Kowloon Tong station.

About a dozen riot police took to the streets in Kowloon’s Tsim Sha Tsui district, normally a haven for local and international shoppers, behind the marchers shortly after news of the petrol bomb attack.

Hong Kong’s metro has borne the brunt of protests, with stations torched and trashed, and only returned to normal operations on Friday after being completely shut down.

The metro normally carries around 5 million people a day.

Hong Kong’s protests started in opposition to a now-abandoned extradition bill but have mushroomed in four months into a pro-democracy movement and an outlet for anger at social inequality in the Asian financial hub.