Eleven people, including separatist Andy Chan Ho-tin, were arrested for possession of explosives and offensive weapons, believed to be connected to violent protests, in two separate crackdowns by Hong Kong police on late Thursday night.

In a media briefing on Friday afternoon, police strongly condemned such unlawful acts, and expressed concerns over escalating violence during anti-extradition-bill protests.

Police believe the escalating violence was linked to radical messages online, which openly advocate the use of violence, and assaulting police officers with deadly means

Li Kwai-wah, Senior superintendent of Organized Crime and Triad Bureau, Hong Kong 

Li Kwai-wah, the senior superintendent of Organized Crime and Triad Bureau, said they believe the escalating violence was linked to radical messages online, which openly advocate the use of violence, and assaulting police officers with deadly means.

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Among the 11 suspects — eight of them aged 24 to 31, including Chan, founder of the banned Hong Kong National Party — were arrested in an industrial building in Sha Tin. They were charged with possession of offensive weapons and possession of explosives without a licence — an offense punishable by up to 14 years in prison. 

Police also discovered gasoline bombs, bows, arrows, steel balls, and materials for making gasoline bombs, according to Acting Deputy District Commander of Sha Tin District Chan Yan. 

Police also found protective gear like gas masks, black and white T-shirts, helmets and kneepads. 

Similar items and weapons were used in violent clashes with police. Chan said police will follow the clues to conduct further investigations. 

At about 10 pm on Thursday, some 200 masked protesters besieged the Sha Tin Police Station, where they wrongly believed that the suspects were held. Another 150 besieged the Ma On Shan Police Station at 1:30 am on Friday, Chan said. 

They tried to storm into the police stations while spraying offensive slogans on the outer wall demanding the release of the suspects. The crowd were dispersed at about 3 am.

Strongly condemning the violent acts, Chan said these radical protesters committed offenses of unlawful assembly and criminal damage. Criminal damage is liable to imprisonment of up to 10 years. 

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The Hong Kong Police Force has the capability and determination to safeguard the city’s law and order by bring offenders to justice, said Li. 

In Tin Shui Wai, another three people — one man and two women aged between 23 to 47 — were arrested for possession of explosives without a licence. 

Police discovered about 30 smoke grenades, some semi-finished, raw materials and about HK$500,000 (US$64,000) cash, according to Li. 

Stressing that police won’t tolerate any violent acts, Li called on the public to speak out against violence. 

READ MORE: HK urged to oppose violence, focus on growth

While the destructive force of the explosives and weapons found are yet to be tested, Li noted that the potential of bows and arrows to cause serious injuries, or even death, to the victims are undeniable. 

In the Yuen Long protest on Saturday, police arrested a man for possession of an imitation gun. If such a gun was used in a large assembly, it could cause unpredictable consequences to public safety because the crowd could have mistaken it for a real gun, Li said.