HONG KONG — Hong Kong settled into an uneasy calm Saturday after violent protests its embattled leader decried as "a very dark day."

All subway and train services were suspended, shops were closed and the streets of the semi-autonomous Chinese territory — usually bustling — were largely empty.

But limited protests continued in defiance of a ban on face masks.

In a televised address, Chief Executive Carrie Lam defended Friday's move to invoke emergency powers in an effort to quell the growing unrest.

"The radical behavior of rioters took Hong Kong through a very dark night, leaving society today half-paralyzed," Lam said in the pre-recorded message broadcast early Saturday.

"The extreme violence clearly illustrated that Hong Kong's public safety is widely endangered," she added.

“Everyone is worried and scared.”

Widespread violence

The decision to ban face masks enraged protesters, who took to the streets to vent their anger.

Many wore masks in defiance through a night that saw widespread violence including arson attacks, vandalism and fights with police.

Demonstrators have been using face masks to conceal their identities and protect themselves from tear gas dispersed by police during months of protests that have roiled the territory.

Police said an officer in the Yuen Long district had fired a shot in self-defense after he was attacked, injuring a protester.

A local hospital confirmed to NBC News that a 14-year-old boy was in serious condition and undergoing surgery after being shot in his left thigh.

The teen became the second victim of gunfire in the protests that began in June.

As pro-democracy protests hit a new level of violence this week, an 18-year-old protester was also shot by a riot police officer on Tuesday. Police defended the use of fire, saying it was a matter of life or death. The injured protester has now been criminally charged.

On Saturday, the United Nations human rights chief called for an “effective, prompt, independent and impartial investigation” into acts of violence, including the shootings.

The protests began in opposition to a bill that would have allowed the extradition of Hong Kong residents to mainland China, but have since spiraled into a broader anti-government movement that has plunged the international financial hub into its deepest crisis since the territory reverted from British to Chinese rule in 1997.

'Endangering our safety'

All train and bus services throughout Hong Kong were suspended late Friday as rail operator MTR shut down the entire network that carries millions of passengers each day.

The network said it was "no longer in a position to provide safe and reliable service," claiming protesters had vandalized and set fires at multiple stations, with two of their station staff attacked and injured.

Over 20 shopping malls around the territory also announced their closure Saturday due to safety concerns.

After widespread violence, the government appealed for a public shift in attitude against rioting Saturday. Laurel Chor / Getty Images

The atmosphere on the streets was much quieter Saturday as hundreds of protesters marched, with some singing “Glory to Hong Kong.”

Many called for a “rest day” in online forums and chats after the night of violence. More protests were expected Sunday.

A protester named Joyce, who refused to give her last name out of fear of repercussions, was still wearing a mask as she marched Saturday near Sogo, one of Hong Kong's biggest malls.

The 34-year-old banker told NBC News she doesn’t accept the ban, which came into effect at midnight.

“This law is endangering our safety,” she said. “Carrie Lam said this anti-mask law is against people who resort to violence, and that she hoped it would de-escalate the situation. However, she never thought about why people are wearing masks even when the protests were peaceful. It is fear and distrust.”

Shielded under umbrellas, hundreds of demonstrators clogged a thoroughfare in Hong Kong's central business district. JORGE SILVA / Reuters

Freelance translator Rose Lu said she believes the ban on wearing masks will only inspire further public anger.

“We had previously said that this law will not solve anything, but the government insists on pushing it forward,” Lu, 28, told NBC News. “It clearly shows that the government is never bothered to listen to its people.”

She was handing out masks as she marched Saturday, but said she was not encouraging people to break the law.

“Whether or not to wear a mask, it’s their freedom,” Lu said.

“If people want to fight against this authoritative regime and to oppose this law, people are welcome to come and take a mask.”

Veta Chan reported from Hong Kong, and Yuliya Talmazan from London.