Hong Kong police fired rubber bullets and tear gas at demonstrators who threw plastic bottles on Wednesday as protests against an extradition bill that would allow people to be sent to mainland China for trial descended into violent chaos.
Tens of thousands of protesters had gathered peacefully outside the Chinese-ruled city's legislature before tempers flared, some charging police with umbrellas.
Police warned them back, saying: "We will use force."
Ambulances sped towards the protest area as panic spread through the crowd, with many people trying to flee the stinging tear gas, according to a Reuters witness. More than 10 people were wounded in the clashes, Cable TV reported.
Police used pepper spray, tear gas and batons to force the crowds back. Some shops put up their shutters at the nearby IFC, one of Hong Kong's tallest buildings.
Civil Human Rights Front, which organized a protest on Sunday that it estimated saw more than a million people take to the streets in protest against the extradition bill, accused police of using unnecessary violence.