Fiery clashes erupted across the city, with security chief John Lee cautioning "unthinkable" consequences if the violence continued.
Authorities have shut down schools, rail links and several businesses in the Asian financial hub as a safety precaution.
On Tuesday night, hundreds of black-clad protesters tried to block riot police from entering the Chinese University of Hong Kong (CUHK) near Tai Po by hurling bricks and petrol bombs.
Trump welcomes Xi to Washington looking for a trade win
US President Donald Trump welcomed Chinese President Xi Jinping to the White House on Thursday for a lavish state summit expected to be heavy on symbolism but light on substance, with both leaders keen to showcase stable ties despite a host of thorny issues.
India's 'cockroach' party threatens protest if election chief doesn't quit in 48 hours
The leaders of India's "cockroach" youth movement said on Thursday that they would launch nationwide protests if India's chief election officer does not resign within 48 hours, after a newspaper report said he had been questioned by his deputies over changes to voter lists.
Russian strikes kill eight in Ukraine, damage maternity clinic
Russian drone and missile strikes on Ukraine's capital Kyiv and its northeast killed eight people on Thursday in attacks that included a maternity hospital and a farm, officials said.
White House reinstates media access following judge's order
The White House said on Thursday it has reinstated journalists from CNN, MS NOW and Politico after a federal judge deemed US President Donald Trump's ban of the three news outlets likely unconstitutional and ordered their access immediately restored.
Australia says OpenAI agent hacked into government website
Australia said on Wednesday an OpenAI agent breached a government health data portal in June, gaining unauthorised access to files, in what could be the first known instance of an AI agent hacking a government website.
Flights operated by Iranian airlines to and from the UAE have been suspended until further notice, according to the General Civil Aviation Authority (GCAA).
More than 10 million meals will be prepared for people in Gaza as part of a major humanitarian initiative honouring the legacy of the late Sheikh Ahmed bin Rashid Al Maktoum, who passed away earlier this week.
The UAE's Operation Chivalrous Knight 3 has launched its annual Winter Clothing Initiative aimed at supporting one million people in Gaza.
