28 September 2014 Last updated at 13:09 ET
The BBC’s Jiuliana Liu says the situation on the ground is “extremely chaotic” and that protesters show no sign of dispersing
Hong Kong police have used tear gas to disperse thousands of pro-democracy protesters near the government complex, after a week of escalating tensions.
Dozens of demonstrators were arrested, with hundreds remaining in the city centre late on Sunday.
Protesters want the Chinese government to scrap rules allowing it to vet Hong Kong’s top leader in the 2017 poll.
Hong Kong Chief Executive CY Leung said the demonstration was “illegal” and elections would go ahead as planned.
China has also condemned the protest, and offered “its strong backing” to the Hong Kong government.
The broader Occupy Central protest movement threw its weight behind the student-led protests on Sunday, bringing forward a mass civil disobedience campaign due to start on Wednesday.