Anti-government protesters attend a demonstration in Wan Chai district, in Hong Kong, China October 6, 2019.

A woman cries as she watches riot police detain an anti-government protester during a demonstration following the government's ban on face masks under emergency law, at Kowloon Tong, in Hong Kong, China, October 6, 2019.

Riot police officers clash with anti-government protesters during a demonstration in Causeway Bay district in Hong Kong, China October 6, 2019.

Riot police officers run towards anti-government protesters during a demonstration in Causeway Bay district in Hong Kong, China October 6, 2019.

An anti-government protester uses a sling shot during a demonstration in Wan Chai district in Hong Kong, China October 6, 2019.

Protesters wearing masks gather during an anti-government rally at Causeway Bay, in Hong Kong, China October 6, 2019.

Masked protesters react in a cloud of tear gas during an anti-government rally in central Hong Kong, China October 6, 2019.

Masked protesters hold umbrellas during an anti-government rally in central Hong Kong, China October 6, 2019.

An inflatable duck is seen during an anti-government rally in central Hong Kong, China October 6, 2019.

A riot police officer clashes with a protester during an anti-government rally in central Hong Kong, China October 6, 2019.

A masked anti-government protester leaves after helping to set a fire at the entrance of a metro station, in Hong Kong, China October 6, 2019.

Anti-government protesters hold bamboo poles during a demonstration following a government's ban on face masks under emergency law, at Sham Shui Po, in Hong Kong, China October 6, 2019.

Anti-government protesters break a window at the entrance of a metro station, in Hong Kong, China October 6, 2019.

Anti-government protesters walk past defaced pictures of Chinese President Xi Jinping and other members of the government, in Hong Kong, China October 6, 2019.

An anti-government protester throws back a tear gas canister during a demonstration in Wan Chai district in Hong Kong, China October 6, 2019.

Flames by a molotov cocktail can been seen on a journalist during a protest in Wan Chai, Hong Kong, China October 6, 2019, in this still image obtained from a social media video. Angus Wong Chun Yiu/via REUTERS.

Anti-government start a fire in a barricade in Mong Kok, Hong Kong, China October 6, 2019.

Riot police officers clash with anti-government protesters during a demonstration in Causeway Bay district in Hong Kong, China October 6, 2019.

A girl wearing a mask is pictured during an anti-government rally at Causeway Bay, in Hong Kong, China October 6, 2019.

Anti-government protesters shelter from the rain under their umbrellas at the start of a demonstration in Tsim Sha Tsui district, in Hong Kong, China October 6, 2019.

A People's Liberation Army soldier holds a yellow banner to warn anti-government protesters during a demonstration following the government's ban on face masks under emergency law, outside Osborn Barracks, in Hong Kong, China, October 6, 2019.

Masked protesters holding umbrellas walk during an anti-government rally at Causeway Bay, in Hong Kong, China October 6, 2019.

An anti-government protester throws an object towards riot police during a demonstration in Wan Chai district, in Hong Kong, China October 6, 2019.

Riot police detain a protester during an anti-government rally in central Hong Kong, China October 6, 2019.

An anti-government protester runs away from tear gas during a demonstration in Wan Chai district in Hong Kong, China October 6, 2019. Image used for illustrative purpose.

A messages is seen on a wall during a demonstration in Wan Chai district in Hong Kong, China October 6, 2019.

A Filipino woman is transferred by rescue workers after she was shocked by tear gas during a demonstration in Wan Chai district, in Hong Kong, China October 6, 2019.