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.
Afghan Taliban says 400 killed in Pakistan air strike on Kabul hospital
At least 400 people have been killed and 250 injured in an air strike by Pakistan on a drug users' rehabilitation hospital in Kabul, a spokesman of the Afghan Taliban government said on Tuesday, a sharp escalation in the conflict between the neighbours.
Bomb attacks kill at least 23 in Nigeria's Maiduguri
At least 23 people have been killed and 108 injured in suspected multiple bomb attacks in Maiduguri city, capital of Nigeria's insurgency-hit northeastern state of Borno, the state police command said in a statement late on Monday.
Five countries warn against major Israeli ground offensive in Lebanon
A "significant Israeli ground offensive" in Lebanon must be averted since it could have devastating humanitarian consequences, Canada, France, Germany, Italy, and Britain have said in a joint statement on Monday.
Fire breaks out at Qatar's Industrial Area after missile interception
Qatar's Ministry of Interior has announced that its civil defence forces are responding to a fire that broke out at its Industrial Area on Tuesday due to fallen shrapnel from a missile interception.
Authorities have responded to an incident involving fallen shrapnel from a ballistic missile interception at Abu Dhabi's Baniyas area on Tuesday, which resulted in the death of one person.
UAE authorities have announced on Tuesday morning that air forces were responding to incoming missile and drone threats from Iran.
Authorities are responding to a fire that has broken out at the Fujairah Oil Industry Zone (FOIZ) early on Tuesday after being targeted by several drones, with no injuries reported.
