Twelve-year-old Samuel was arrested one summer evening while trying to flee from riot police at a protest. He was tackled to the ground, sat on and handcuffed by officers and accused of taking part in an illegal assembly. During the arrest, an officer stepped on his hand.

In custody, Samuel was terrified. Police found in his bag a gas mask, helmet, spray paint and gloves. Officers shouted at him and called him a “junior cockroach”, a name used to put down protesters.

“I was so frightened and thought they might beat me to death,” he said. It was nearly midnight, several hours after his arrest, when police notified his parents and sent him to a hospital for his injuries.

Samuel* is one of tens of thousands of youths who have taken part in Hong Kong’s anti-government movement, now in its sixth month. Filled with a passion to “save Hong Kong”, many say they are willing to give up their lives to fight for democracy and freedoms in the Chinese-ruled city, where Beijing has been increasingly asserting its political and economic influence.

Recent weeks have seen the most violent incidents so far, with thousands more arrested after clashing with police around university campuses after protesters blocked roads and threw molotov cocktails. On Sunday police made arrests – including a secondary school girl and a 16-year-old boy – as small groups of pro-democracy activists targeted some of the city’s shopping centres.

Officials said as of 5 December, of the 5,980 people arrested since the movement started in June, 2,383 or 40% were students and 367 of them have been charged. Among them, 939 were under 18, with the youngest being only 11, and 106 have been charged. Suspects have been arrested for a range of offences including rioting, unlawful assembly, assaulting police officers and possessing offensive weapons.

Legal experts say Hong Kong law’s definition of “illegal assembly” and “rioting” – defined as an unlawful assembly of three or more people where any person “commits a breach of the peace” – is vague and ill-defined.

If the authorities hoped arresting young protesters would deter them, it is having the opposite effect. Samuel, who was released on bail, said his hatred for the police had deepened since his detention. He said he had not participated in violent acts himself but he endorsed other protesters’ actions, including attacks on police officers.

“The police beat protesters like mad. They deserve it,” he said. “Don’t hassle me and I don’t hassle you.”

Samuel acknowledged that taking part in the increasingly violent movement was risky but insisted he was driven by his love for his home.“It’s my responsibility to do something for Hong Kong,” he said. “I’ve been scared once already. What else is there to be scared of?”

‘I want to give all I have to Hong Kong’

Samuel’s sentiments are echoed by other young protesters. James, 13, and Roderick, 16, from elite schools and middle-class families, are among the youngest people to have been charged over the protests. They were arrested in a protest shortly after others had thrown molotov cocktails – a scene that would be defined as a “riot” under Hong Kong law.

They said an incident on 21 July when thugs indiscriminately attacked passengers at the out-of-town metro station while police were nowhere to be seen had led to a breakdown of their trust in the authorities. After that, they went to the frontline of the protests, braving teargas and confrontations with police.

The teenagers said the police’s escalating use of force – including more than 16,000 canisters of teargas, water cannon, 10,000 rubber bullets and live rounds – and the authorities’ refusal to investigate police’s abuse of power were what prompted them to take part in the increasingly violent protests. They see protesters’ attacks on riot police as justified because they can no longer trust the police to deliver justice.

“We don’t attack unless we’re attacked,” James said. “We can’t just stand there and not do a thing.”

Both boys carried wills when they went out to protest. “I was always scared – whether I would get shot, get arrested or even lose my life. But if we don’t come out because we’re afraid, there would be even fewer people out there,” James said.

“I really want to give all I have to Hong Kong,” the 13-year-old said, his eyes welling up in tears. “When you pursue freedom, sacrifices are unavoidable. “We are halfway into the gate of hell. We’ve put our future and career on a line, but it is worth it.”

If convicted, James is unlikely to be jailed because of his age, but he risks being sent to a children’s home and having a criminal record.

Roderick said the solidarity, unity and mutual support he had experienced were the key attractions of the movement. “To see young people working towards the same ideal and same goal – that’s the most beautiful picture I’ve ever seen.”

At 16, Roderick also faces an uncertain future, but said he would not give up on the goal of democracy for Hong Kong. “It’s a gamble, but if we don’t even try, we would lose for sure,” he said.

Dr Jeffrey Murer, an expert on youth mobilisation at the University of St Andrews in Scotland, said it was often young people’s overwhelming desire to change the world for the better and their profound lack of trust in institutions that prompted them to gamble on their future.

“The social contract has broken down and people feel obligated to defend their rights and identity,” he said. “These young people have taken on a strong Hong Kong identity and feel the institution is not defending them.”

He said the political crisis had also shaken their sense of stability. Their feeling of “no future” and the profound threat to their identity had prompted them to take risks to defend themselves.

Stephen Chiu, a sociology professor at the Hong Kong Education University, said ideology and mutual emotional support among young people had sustained their high-risk and high-cost social actions.

When they perceived “so much absurdity on the government’s part and the other side is acting excessively, they question why they have to be constrained by their normal moral standards,” he said.

“It’s a war situation – they are willing to die for their homeland. There are many examples in history. Whether you agree or not, there is a higher call and the protesters have a set of values some feel it’s worth dying for.”