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.
8 Israeli airstrikes hit Syria's Abu al-Duhur airbase, state TV reports
Eight Israeli airstrikes have hit the Abu al-Duhur military airbase in northwestern Syria early on Tuesday, targeting the runway and storage facilities, Syria's state-run Ekhbariya said, citing a military source.
Two killed in high school shooting in southern Philippines
Two students were killed in a shooting at a high school in the southern Philippines on Tuesday, one of them the gunman, officials said, in the second such incident in the country in less than two months.
Pakistan top court orders ex-PM Imran Khan be moved to hospital from jail
The Supreme Court of Pakistan has ordered on Tuesday that former Prime Minister Imran Khan be moved to hospital from jail, his Pakistan Tehreek-e-Insaf party said, meeting a longstanding demand of his party and family, who had raised concerns about his health.
Russian missile attack kills 10 in Ukraine's Kharkiv region, governor says
A Russian missile attack has killed 10 people and injured a further eight in a village in Ukraine's northeastern Kharkiv region, the regional governor said on Tuesday.
Trump says Iran won't make deal he thinks is needed
President Donald Trump said on Monday Iran would not make the deal he thinks is needed to end a war with the US and should surrender as talks between the countries remained stalled.
