Thousands of people had gathered in a demonstration, which lacked permission, against police violence. The protesters gathered at the port of the Kowloon area of ​​Hong Kong. The police were there early and urged them to move away from the area, but despite this, the number of people was growing rapidly.

Many fled the scene when riot police met the protesters with tear gas and pepper spray. Several people were arrested and unrest later erupted when protesters and police clashed.

Bombs against police station

Police say they were attacked with umbrellas, that petrol bombs were thrown at a police station and that stores were set on fire.

"Some threw smoke bombs at MTR (metro) exits," the police write.

Witnesses have also seen two entrances to subways on fire, according to Reuters.

Been going since June

The protests in Hong Kong have been going on since June and were triggered by a bill to allow extradition of suspected criminals to the central government in China. The demonstrations have since widened with demands for democracy reforms and looser rein from Beijing.

The protests have often ended in violence and several protesters and some journalists have been injured. The port movement accuses the Hong Kong police of assault - which the police have denied.