Updated: July 22, 2019, 8:06 p.m.
Ken Bredemeier and Megan Duzor contributed to this report.
STATE DEPARTMENT — Anger is growing in Hong Kong over an attack on pro-democracy protesters by suspected gangsters that left dozens of people injured.
Cellphone video on social media shows white-clad assailants alleged to be Triad gangsters attacking commuters with pipes and poles at a Hong Kong subway station Sunday.
The United States is calling all sides to "exercise restraint," adding organized violence by criminal gangs against private citizens is "particularly disturbing."
In Beijing, officials said the Chinese government firmly supports the Hong Kong government in taking all necessary measures and punish the criminals. Beijing also reiterated it firmly opposes any "foreign interference" and "any wanton accusations" on Hong Kong's internal affairs.
Hospital officials say 45 people were injured in the violence, with one in critical condition. Activists and local politicians accused police on Monday of being slow to respond to the scene.
Hong Kong's embattled leader Carrie Lam said allegations that police had colluded with the assailants were "unfounded.''
Sunday's attack came during a night of escalating violence in Hong Kong that also saw clashes between anti-government protesters and police. Protesters defaced the Chinese national emblem on Beijing's liaison office during a massive demonstration Sunday, drawing anger from China.
"Actions by some radical demonstrators have affected the bottom line of the 'one country, two systems' principle," a Chinese foreign ministry spokesman said Monday, referring to Hong Kong's special status under the terms of its 1997 handover from Britain to China.
Some protesters threw eggs at the liaison office and spray-painted surrounding security cameras, as tens of thousands of demonstrators took to the streets. Hong Kong riot police fired tear gas and rubber bullets late Sunday to disperse protesters.
Sunday's chaos followed a familiar pattern over the last several weeks, starting with a huge peaceful protest that evolved into a night of clashes between police and more hard-core groups.
American officials have said the ongoing demonstrations in Hong Kong reflect the sentiment of Hong Kong's people and their broad concerns about the erosion of Hong Kong's autonomy.
"It is important for the Hong Kong government to respect the freedoms of speech and assembly, as guaranteed by the basic law," the United States said Monday.
"Societies are best served when diverse political views are respected and can be freely expressed," a State Department spokesperson told VOA on Monday.
At the White House, U.S. President Donald Trump said on Monday he hoped Chinese leaders "will do the right thing."
"They've been out there protesting for a long time. I've never seen protests like it," Trump told reporters at the White House before an unrelated meeting with Pakistani Prime Minister Imran Khan.
"I think President Xi [Jinping] of China has acted responsibly, very responsibly," said Trump, adding, "I hope that President Xi will do the right thing."
The British government on Monday condemned the violence during Sunday's protests, but defended the right of protesters to assemble peacefully.
"We must not let the violent actions of a few overshadow the fact that hundreds of thousands of people took part in the march yesterday and did so in a peaceful and lawful manner," said Andrew Murrison, British Minister of State for the Middle East and Minister of State for International Development.
The protests have morphed from a call to end to the now-suspended bill to extradite Hong Kong residents charged with criminal offenses to China for trial into demonstrations for democratic reforms and an end to Beijing's tighter grip on the territory. Many shouted, "Liberate Hong Kong!"
It is the worst social turmoil to rock the former British colony since it returned to Chinese rule 22 years ago.
Lam has apologized for the turmoil the extradition bill has caused and declared it "dead."