A group of pro-democracy politicians in Hong Kong have filed a legal challenge against the government’s use of a colonial-era emergency law to criminalise face masks at protests.

The mask ban, which came into effect at midnight on Friday, triggered an overnight rash of widespread violence and destruction in the city.

Fires were lit and an off-duty police officer who was attacked fired a live shot in self-defence that injured a teenage protester.

Anti-government protesters set up a barricade during a rally after the government invoked an emergency powers to ban masks at demonstrations.

Two activists failed to obtain a court injunction on Friday against the ban on face coverings, which the government says make it tough for police to identify radical protesters.

In a second bid, Dennis Kwok said a group of 24 legislators filed a legal appeal to block the anti-mask law on wider constitutional grounds.

He said the city’s leader Carrie Lam acted in bad faith by bypassing the Legislative Council, Hong Kong’s parliament, in invoking the emergency law.

Henry the VIII

“This is a ‘Henry the Eighth’ situation. This is basically ‘I say what is law … and I say when that ceases to be law’. That’s not how our constitution works,” Mr Kwok said.

The court will hear the case on Sunday morning.

Hong Kong Chief Executive Carrie Lam takes part in a press conference in Hong Kong.

Ms Lam has said she will seek the council’s backing for the law when its session resumes on 16 October, and she has not ruled out further measures if the violence continues.

In a televised address broadcast as protesters again marched in masks on Saturday, a solemn Ms Lam described Hong Kong as “semi-paralysed” and reiterated the mask ban is needed to stop the violence.

Riot police deploy tear gas against protesters who openly defied a ban on face coverings.

“The government needs to take drastic measures to say no to violence, restore peace in society, protect citizens’ right to continue their daily lives and freedom, not allowing a small group of rioters to destroy it,” she said.

Many shopping centres, shops and the entire MTR network of subways and trains that usually handle more than four million trips a day shut on Saturday following the overnight rampage.

Many peaceful protesters say violence has become a means to an end, the only way for young masked protesters to force the government to bend to clamours for full democracy and other demands.

But the teen’s shooting on Friday night – the second victim of gunfire since the protests began in early June – stoked fears of more bloody confrontations.

An 18-year-old protester was also shot at close range by a riot police officer on Tuesday.

Police said in a statement on Saturday the 14-year-old, who was hospitalised with a gunshot wound on his thigh, has been arrested for participating in a riot and assaulting a policeman.

Police have said they are still investigating exactly how he was shot.