Anti-government protesters burn a banner that commemorates the 70th anniversary of the founding of the People's Republic of China, in Central Hong Kong, China, October 4, 2019.

An anti-government protester wears a mask made with a FedEx envelope during a demonstration in Hong Kong, China, October 4, 2019.

Anti-government protesters wear masks during a demonstration after government's ban on face masks under emergency law, at Mong Kok, in Hong Kong, China, October 4, 2019.

Anti-government protesters open umbrellas to block people to photograph during a demonstration after government's ban on face masks under emergency law, at Mong Kok, in Hong Kong, China, October 4, 2019.

An anti-government protester covers their face, after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Hong Kong, China October 4, 2019.

Anti-government protesters vandalise the metro entrance in Causeway Bay district in Hong Kong, China, October 4, 2019.

Firefighters try to extinguish a fire set by anti-government protesters, after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Wong Tai Sin district, in Hong Kong, China October 4, 2019.

Anti-government protesters run away from a tear gas canister, after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Wong Tai Sin district, in Hong Kong, China October 4, 2019.

Anti-government office workers wearing masks attend a lunch time protest, after local media reported on an expected ban on face masks under emergency law, at Central, in Hong Kong, China, October 4, 2019.

Anti-government protesters vandalise a mobile phone store, after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Hong Kong, China, October 4, 2019.

An anti-government protester wears a mask during a demonstration in Wong Tai Sin district, in Hong Kong, China October 4, 2019.

Anti-government protesters block a street in Central Hong Kong, China October 4, 2019.

A masked anti-government protester sets a trash can in Hong Kong, China, October 4, 2019.

Anti-government protesters block one of the entrances to the metro station at Causeway Bay, after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Hong Kong, China, October 4, 2019.

Anti-government protesters wearing masks smash Mong Kok Mass Transit Railway (MTR) station during a demonstration after government's ban on face masks under emergency law, at Mong Kok, in Hong Kong, China, October 4, 2019.

An anti-government protesters stand behind a column of water from a fire hydrant, after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Wong Tai Sin district, in Hong Kong, China October 4, 2019.

Riot police chase away anti-government protesters near Causeway Bay metro station, after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Hong Kong, China October 4, 2019.

An anti-government protester stands near a fire, after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Wong Tai Sin district, in Hong Kong, China October 4, 2019.

Anti-government protesters set on fire one of the entrances at the metro station at Causeway Bay, after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Hong Kong, China, October 4, 2019.

Anti-government protesters carry their friend who was shot by rubber bullets after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Wong Tai Sin district, in Hong Kong, China October 4, 2019.

Anti-government protesters block a street in Central Hong Kong, China, October 4, 2019.

A bureau of Industrial and Commercial Bank of China (ICBC) is seen smashed by anti-government protesters after government's ban on face masks under emergency law, at Mong Kok, in Hong Kong, China, October 4, 2019.

An anti-government protester wearing mask smashes a bureau of Bank of China during a demonstration after a government's ban on face masks under emergency law, at Mong Kok, in Hong Kong, China, October 4, 2019.

Anti-government protesters smash windows at a government office, after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Wong Tai Sin district, in Hong Kong, China October 4, 2019.

An anti-government protester sets on fire one of the entrances to the metro station at Causeway Bay, after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Hong Kong, China, October 4, 2019.

Anti-government protesters burn a banner that commemorates the 70th anniversary of the founding of the People's Republic of China, in Central Hong Kong, China October 4, 2019.

An anti-government protester wearing mask smashes the logo of MTR during a demonstration after government's ban on face masks under emergency law, at Mong Kok, in Hong Kong, China, October 4, 2019.

Water from a fire hydrant spill inside MTR station after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Wong Tai Sin district, in Hong Kong, China October 4, 2019.

An anti-government protester throws a rock into a vandalised store in Hong Kong, China, October 4, 2019.

An anti-government protester wears a mask as he sets a fire outside Mong Kok Mass Transit Railway (MTR) station during a demonstration after government's ban on face masks under emergency law, at Mong Kok, in Hong Kong, China, October 4, 2019.

Anti-government protesters run carrying barriers as they block a street in Central Hong Kong, China, October 4, 2019.

Anti-government protesters block the roads in Central Hong Kong, China, October 4, 2019.

Anti-government protesters vandalise a mobile phone store, after leader Carrie Lam announced emergency laws that would include banning face masks at protests, in Hong Kong, China, October 4, 2019.