Three 17-year-olds have admitted taking part in a riot at the Singapore Boys' Home last September, an act of violence that caused damage exceeding $10,000.

A district court heard yesterday that three men working at the home were also assaulted. A 44-year-old auxiliary police officer was injured in one eye that most likely would be permanently damaged. A 33-year-old youth guidance officer and the home's 45-year-old assistant manager suffered head injuries.

The rioters cannot be named, owing to a gag order by the court, so The Straits Times will identify the trio, who were convicted yesterday, as A, B and C. Each of them pleaded guilty to a rioting charge and two counts of vandalism.

They were the first ones to be convicted at the State Courts for participating in the riot.

The court heard that the trio were sent to the home in Jurong West after they committed a range of offences, including theft.

On Sept 26 last year, there was a shouting match among the inmates of the home and the teenagers were placed on lockdown for the entire day. They were not allowed to leave their dormitories apart from attending classes.

Said Deputy Public Prosecutor Timotheus Koh: "They were angry with the punishment imposed and started discussing a plan to riot, through the grilles of their adjacent dormitories. During the discussion, it was suggested the group carry out 'armour bang', a common term for the banging of items in dormitories and causing damage."

The inmates were informed later in the evening that they would no longer be on lockdown the following day.

But on Sept 28, two days after the lockdown, one of the inmates became restless during yard time. He gathered the others, including the trio, and told them of his plan to proceed with the "armour bang". They agreed to riot during fall-in time as this was when everyone would be gathered together.

Around 5.50pm, the youth guidance officer called for everyone to fall in at the home's courtyard. As planned, A and a 15-year-old boy started a fake argument and A challenged the younger teen to a fight.

When the officer tried to separate them, the 15-year-old punched the man's face, and the other teens, including the trio, joined the attack. The assistant manager and the auxiliary police officer, who tried to help the man, were also attacked by the teens.

The DPP said C used a floorball stick to hit the assistant manager in the back of his head. A struck the auxiliary police officer's head with a similar stick multiple times.

The injured adults eventually fled the scene.

The trio and four other rioters also took turns to damage property at the home, including a wall-mounted television set and two bookshelves. Four more teens later joined the group.

The police were called, said DPP Koh, adding: "The group... broke into song and shouted loudly while waiting for the police to apprehend them."

The court has called for reports to assess the teenagers' suitability for reformative training, which involves a strict regimen that includes foot drills and counselling.

A and C will be back in court next week. B's case has been adjourned to next month.