Hong Kong police have arrested protesters on the eve of Chinese President Xi Jinping‘s visit to the city to commemorate the 20th anniversary of its handover from Britain to China.

The demonstrators had gathered around the Golden Bauhinia statue to express their frustration with what they perceive as Beijing’s encroachment on democratic values.

Those detained include a handful of young activists who were propelled into the international spotlight during the 2014 Umbrella Movement, when thousands poured into the streets, occupying major commercial areas of Hong Kong for 79 days.

Pro-democracy party Demosisto confirmed that the police picked up at least seven of its members, including Umbrella Movement leaders Nathan Law, Joshua Wong and Agnes Chow.

Law, 23, won a seat on Hong Kong’s Legislative Council in September, making him the city’s youngest ever legislator.

Videos and images on social media showed police dragging protesters, including Wong and Law, out of the area. Some of them shouted “I want real universal suffrage” as they were being taken away.

@2legit2trip: Joshua Wong violently dragged out of Bauhinia Square into that police van awaiting arrest #BlackBauhinia #hk20

Earlier on Wednesday, Wong reiterated his call for direct election and nomination of the chief executive, the head of the local government. In Hong Kong’s most recent election, eligible citizens could cast votes, but only for candidates that had been nominated by a committee filled with Beijing loyalists.

China argues that this process qualifies as universal suffrage, since all eligible voters are able to cast a ballot, but pro-democracy advocates disagree, arguing that screening of candidates undermines the democratic process.

The bauhinia became the emblem of Hong Kong in 1997. The central government gave the statue to Hong Kong as a gift that year to mark the handover and the city’s transition to a special administrative region. The monument remains a tourist attraction, especially for those visiting from mainland China.

@joshuawongcf: We cover up statue symbolizing Hong Kong’s return to Communist rule to against Beijing’s suppression on HK democracy ahead of Xi visit.

Earlier this week, demonstrators shrouded the Golden Bauhinia in black cloth to express their concern about declining autonomy in the special administrative region.

“Our confidence in ‘One Country Two Systems’ has waned and is replaced by the fear of it becoming ‘One Country 1.5 Systems,'” Demosisto said in a Monday statement.

Xi is expected to arrive in Hong Kong on Thursday.

The police department did not immediately respond to CNBC’s request for comment.