HONG KONG (AP) — Hong Kong pro-democracy activists Joshua Wong, Agnes Chow and Ivan Lam were sentenced to jail on Wednesday on charges related to an unauthorized anti-government protest last year at the city’s police headquarters.

Wong, who pleaded guilty to organizing and participating in the protest, received 13 1/2 months behind bars. Chow, who also pleaded guilty to participating in the protest and inciting others to take part, received 10 months, while Lam received 7 months after pleading guilty to incitement.

The protest took place on June 21 last year, and saw thousands surround the police headquarters as they demonstrated against excessive force by police against protesters, as well as a now-withdrawn extradition bill that would have allowed suspects to be extradited to mainland China.

The jailing of the trio, known for their advocacy for democracy in Hong Kong both at home and abroad, comes as Beijing tightens control over the semi-autonomous city following months of anti-government protests last year, which occasionally saw violent clashes between protesters and police. In June, Beijing imposed a sweeping national security law on Hong Kong to crack down on dissent.

It is the first time that Chow, 23, has been given a jail sentence. Wong, 24, and Lam, 26, had previously been jailed over charges related to their activism.