The day all hell broke loose at high school

IT WAS 8.50am on a Monday, as the students of Merrylands High School milled in the schoolyard for assembly when five boys arrived, uninvited, seeking revenge.

For 10 minutes the teenage gang tormented and terrorised anyone unable to escape its path, smashing 100 windows and leaving a damage bill of almost $27,000.

The story of the rampage can be told today for the first time.

In Parramatta Children's Court on Friday, the five pleaded guilty to charges including assault, affray and causing malicious damage to property arising from the rampage on April 7 this year. Only one of the teenagers appeared in court, with four appearing via video link.

Police facts tendered to the court and obtained detailed how the violence was sparked by a girl - the cousin of one of the gang members - being physically assaulted by a teenage boy.

Seeking vengeance, a 14-year-old from Auburn, two 15-year-olds from Carramar and Merrylands and two 16-year-olds from Merrylands and Seven Hills went to school believing their quarry - a boy called "L" - was a student there.

It was the start of a typical week, with the school community gathering for Monday assembly. More than 700 students and their teachers were in the school quadrangle. While the school has security fencing, the gates were open for students who were running late.

Chaos erupted when the five boys, dressed in jeans and hooded jumpers, joined the assembled student group.

Holding a samurai sword with a 61-centimetre blade, the leader of the boys confronted a male student and punched him in the face with his free hand. His cohorts, armed with baseball bats and a machete, slowly ambled through the lines of students. Two girls were struck on the legs by baseball bats.

A teacher called out the alarm and panic-stricken students were sent to their classrooms as the school went into lockdown.

The sword-wielding leader approached a female student and held the weapon 40centimetres from her throat, demanding to know where "L" was hiding.

"The girl replied: 'Who?"'. She was punched in the face, police said.

A senior teacher named Henry remonstrated with the attacker on the quadrangle.

"You cannot do this," he said. "You have to leave."

The attacker brandished the sheathed sword at the teacher and then swung the weapon. The sword struck the teacher on the left side of his torso. In pain, the teacher grabbed on to the sword with his armpit and tried to wrestle the weapon away from the teenager.

Other gang members came to the aid of their leader and struck the teacher on the head from behind with another weapon.

The teacher fell forward and accidentally unsheathed the sword as the boys stormed off.

From the quadrangle they went to the canteen and confronted the school cleaner, a man called Gary.

The gang leader lifted the sword above his head. "I bet this will hurt you," the teenager screamed, before moving on.

The five boys then entered a two-storey school building. They smashed windows along the entire length of the upstairs and downstairs corridors of the building, sending shards of glass flying into adjoining classrooms. They then stopped outside locked room 33 on the ground floor, and made a decision that threatened to escalate the violence to tragedy.

The gang smashed down the locked door and stormed into the classroom where 20 students and a teacher were sheltering. They began smashing windows as students cowered under their desks and screamed for help.

Suddenly, a senior police officer entered with his baton drawn. He demanded that the assailants drop their weapons. When they refused he drew his gun and again demanded they put the weapons down. The teenage boys slowly dropped their weapons and raised their hands.

It was 9am. Ambulances were rushing to the school. The assaulted teacher was taken to Westmead Hospital with bruising to the back of his head, but was released in the afternoon. Two students, one boy and a girl, were also taken to hospital.

Ambulance NSW said 18 students were treated for "minor injuries, some lacerations, some bruising".

Detective Sergeant Gary James, who headed the police investigation into the lockdown, said the actions of school principal Liliana Mularczyk and her staff had prevented a mass tragedy. The rampage was over.

Police wanted boys tried as adults

NSW Police wanted the five teenagers to be tried as adults but were turned down.

In special circumstances police can request a more severe jail term - in this case up to 10 years for the charges of affray.

The police were deeply disturbed about the school system being used to play out violent rivalry between groups of students and believed the actions of the teenagers deserved special attention.

But The Director of Public Prosecutions referred the matter to the Children's Court. On Friday, Magistrate Gabriel Fleming remanded the boys to appear in Parramatta Children's Court on September 24 for sentencing after they pleaded guilty.

In the Children's Court the maximum sentence on the charge of affray - the most serious levelled against the boys - is three years, compared to up to 10 years for adults.

Dr Fleming permitted 'some' media to cover Friday's hearing, despite protests from the legal representatives of the defendants. She said the matter was in the public interest.

Under laws governing media coverage in the Children's Court, the names of defendants cannot be made public.