A counter-terrorism exercise by police, the Fire Service Department and the Hospital Authority on the extensive campus brought together more than 100 students from different middle schools on Sunday.

And Anchors Academy's security staff also joined in the drill.

The police mobilized over 100 constables from its New Territories North region and rolled in a mainland-made Saber-Toothed Tiger vehicle for the drill.

The force showcased various anti-terrorist equipment, such as bulletproof shields and vests and door-breaking tools before the exercise. Some participants tried on the vests and had themselves pictured if they liked the look.

The drill was based on the idea that students and teachers were attending a lecture in the auditorium when terrorists smashed their way into the campus and opened fire on the auditorium.

Constables from the Emergency Unit and Counter Terrorism Response Unit then exchanged fire with the terrorists. Some were shot down, and then paramedics arrived to attend to casualties as students and teachers escaped, sheltering in classrooms on the third floor, locking doors and reporting their locations to police. That fitted the terrorist attack response principles of "run, hide and report."

Meanwhile, terrorists wandered the corridors, intimidated other students and teachers and tried to break into the locked classrooms before officers arrived and coralled all the bad guys. Officers then searched classrooms for students and teachers.

The drill ended after police set up an affected person center to check and register those caught in the attack while medics treated casualties.

Police assistant commissioner Lui Kam-ho described the drill as "unprecedented" and explained: "It was vital we could have hundreds of teenagers and members of the public joining our drill.

"The drill deepens understanding of the police but also enables them to know how different forces collaborate in the face of a terrorist attack."

While Hong Kong has been mercifully free of terrorist attacks, Lui noted, such events have happened on foreign campuses occasionally, and the danger cannot be neglectable.

Lui noted too that "run, hide and report" are not only applicable to terrorist attacks but can figure in all emergencies and violence, and he urged people to follow the principles when encountering danger.

A student participant named Lee said he now knew more about responding to emergencies, and he would hoped to escape calmly if ever facing danger.

And student Ng said he was most impressed by the exchanges of gunfire between police officers and the terrorists.

He highlighted the facts that some officers stopped bullets with the shields while some threw flash bombs while others shot back.

"The collaboration among officers was really admirable," he said.