In Hong Kong, pro-democracy demonstrators have been met with tear gas and arrests by police attempting to clear a road being blocked by the protestors.
Harcourt road in the city's government district turned into chaos as demonstrators and police engaged in sporadic clashes. The first attempts to move protestors using pepper spray were unsuccessful.
The demonstration was organised to protest Chinese involvement in Hong Kong's internal political structures.
The occupation of central Hong Kong was scheduled to start in three days time but was moved forward, with the leader of Occupy Central Benny Tai telling the crowd:
I've got a long-awaited message; Occupy Central will start now.
Students and people who support democracy have begun a new era of civil disobedience.
The action follows student protests over the past week. Tensions have escalated rapidly with 60 students arrested in past 48 hours.
The movement is calling on China to allow the people of Hong Kong to choose their own Chief Executive without interference from Beijing.
In August, the Chinese Communist Party allowed the people of Hong Kong to elect their Chief Executive but they must choose from candidates put forward by the Communist party. Furthermore, the candidates must profess their "love" of China and its political system.
Hong Kong Chief Executive CY Leung said the protest was "illegal" but that the government was "listening attentively to members of the public".
Hong Kong retains more autonomy than mainland China under agreements made after the British handover of the former colony in 1997.