Tear gas has been fired by Hong Kong riot police at an unauthorized protest held by tens of thousands of people to condemn an attack by armed masked men last week.

As a small group of protesters refused to disperse in the northern district of Yuen Long, police fired rubber bullets.

The protest took place where pro-democracy protesters had been attacked by suspected triad gang members.

Police have been accused of turning a blind eye and colluding with the attackers, claims they deny.

There were seven weeks of anti-government and pro-democracy protests in Hong Kong sparked by a controversial bill that would have enabled extraditions to mainland China.

The government has since halted the legislation but protesters have demanded its complete withdrawal, as well as an inquiry into police violence, democratic reform, and that Hong Kong’s leader Carrie Lam resign.

Hong Kong Protests: Hundreds of Demonstrators Storm Parliament Building on Anniversary of Chinese Rule

Hong Kong protests: Schools and banks closed as demonstrators block downtown

Hong Kong clashes near government offices

The July 27 rally had been banned by the police, a highly unusual move in the territory, where protests are usually allowed.

Police say they refused permission because they feared violent clashes between protesters and residents.

The march was planned as a response to last Sunday’s attack, in which about 100 men descended on Yuen Long’s metro station, beating protesters – as well as passersby and journalists – with wooden and metal sticks.

The attack left 45 people injured and was widely blamed on triad gang members. They appeared to target those wearing black, the color people had been told to wear for the protest.

Triads are known to be active in Yuen Long – located in a rural northern district in Hong Kong, near mainland China – and many local villagers have also expressed opposition to the pro-democracy protests.

Tens of thousands defied the police ban and approached Yuen Long on July 27, marching down some of the main roads.

Police observed and filmed the start of the protest, and riot police could be seen on standby.

They said some protesters were holding iron poles and shields, and “even removing fences from roads”.

Some protesters also surrounded and vandalized a police vehicle, “causing danger to the life of the police officers on board”, they said.

Shortly after 17:00 local time, police began firing several rounds of tear gas in an attempt to disperse the crowd.

The protesters – most wearing masks and hard hats – threw projectiles and swore at police – but also parted to allow ambulances to go through.

Later in the evening, in an attempt to clear several hundred demonstrators, police fired rubber bullets, injuring at least nine people, according to the AFP news agency.

Protesters have been demanding an independent inquiry into police violence, saying police used excessive force in several anti-extradition bill and pro-democracy protests.

Demonstrators and pro-democracy legislators have alleged that the authorities – including the police and pro-government legislators – had advance knowledge of the attack.

Police say suggestions that they colluded with criminal gangs were a “smear”, and that 12 people have so far been arrested, including nine men with links to triads.

There have also been growing tensions between protesters and pro-Beijing groups.

Earlier this week, pro-Beijing legislator Junius Ho’s office was ransacked, and his parents’ graves were vandalized.

Junius Ho had come under criticism after video footage showed him shaking hands with white-shirted men on July 27 shortly before the attacks.

He said he did not know about the attack, but defended the men, saying they were simply “defending their home and people”.