In a press conference yesterday afternoon, Police Commissioner Stephen Lo Wa-chung said the officer who opened fire had made a judgement that the officer considered correct, based on the circumstances on the ground at the time.

“Rioters attacked a police officer with hard objects and threatened his life. He fell on the ground and was kept being attacked by the rioters,” Lo said.

“With no alternatives, my colleague used his firearm in accordance with the use of force principle to prevent his colleague from being further attacked and also for his own personal safety.”

Video footage of the incident on Argyle Street showed two officers drawing their weapons and pointing them at the mob at around 2am on Tuesday. One of them was seen firing two shots into the air as the rioters hurled bricks, glass bottles and wooden boards at them.

Lo stressed that his officers followed strict guidelines on the use of force, and the strictest training when it came to the use of firearms.

According to the Police General Orders on the use of force, officers can use firearms when anyone’s life is threatened, to suppress a civil disturbance or riots, or when the target is believed to have committed a serious offence and warrants arrest.

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Junior Police Officers’ Association spokesman Tung Yiu-ming said the the traffic officer had been justified in drawing and firing his weapon as his colleague was in real danger and he needed to stop the rioters.

“Firing at the crowd will make great injuries and therefore, he made the right choice to fire into the air,” he said.

But some raised concerns as to whether “warning shots in the air” were actually allowed as they might cause serious injuries to others in such a densely packed city.

“If a decision is made to open fire, it must be aimed and at the target,” said a veteran police officer.

“We are never taught to fire warning shots and could only give verbal warnings or by waving banners. Firing into the air might hurt someone when [the bullet] falls back down,” echoed another one.

Tung, however, said these could not be classified as warning shots as enough of verbal warnings had been given and officers on the scene needed to take immediate action to stop the mob.

Another top police source, of directorate rank, echoed that claim: “When repeated verbal warnings, batons and pepper spray failed to control the rioters, the gun was the only thing left that a traffic officer could use.”

The police chief said a full investigation would get to the bottom of the matter.

“All I have got are from the screen shots of the TV news,” Lo said. “I will conduct a full investigation into the incident so that I will have a better understanding of what the officer was considering at that time.”

The police chief also rejected accusations that his officers had been ill-prepared for the riots and underestimated the gravity of the situation in leaving officers outnumbered by hundreds of rioters.

Lo insisted adequate manpower had been deployed.

“There is absolutely no delay in supporting our officers in the frontline,” he said. “But the situation can change in a few seconds and we must realise it takes time for officers going from one district to another.”