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.
Hong Kong court finds tycoon Jimmy Lai guilty in landmark security trial
Hong Kong's High Court on Monday found pro-democracy campaigner Jimmy Lai guilty of conspiracy to collude with foreign forces and to publish seditious material under a China-imposed national security law that could see him jailed for life.
School bus accident in Colombia kills 17, injures 20
Seventeen people were killed and 20 injured after a bus carrying school children fell off a cliff in a rural area in northern Colombia, the local governor said on Sunday night.
Australia plans tougher gun laws after father and son kill 15 at Bondi Beach
Australia signalled plans for tougher gun laws on Monday as the country began mourning victims of its worst mass shooting in almost 30 years, in which a father and son duo killed 15 people at Sydney's Bondi Beach.
Police to release man detained over Brown University mass shooting
The man held as a "person of interest" in the Brown University shooting that left two students dead and nine injured will be released from custody, authorities said on Sunday night.
Shooting at Australia's Bondi Beach kills 12
At least 12 people were killed and almost 30 wounded when gunmen opened fire at Sydney's Bondi Beach on Sunday in what Australian police and officials described as a terrorist attack.
