Clashes have broken out in Hong Kong's Mong Kok district as police cleared illegal food stalls set up for Lunar New Year celebrations.
Violence erupted overnight as food and hygiene inspectors tried to remove vendors from the junction of Portland Street and Shan Tung Street.
Angry protesters threw bricks and other missiles at police, who used batons and pepper spray.
A senior official said police fired two warning shots in to the air.
Acting District Commander Yau Siu-kei also said 44 people, including police, were injured. At least 23 people were arrested.
Hong Kong's government condemned the violence, saying the "mob" had numbered several hundred people and that those involved would be brought to justice.
It is the largest unrest in Hong Kong since the massive pro-democracy street protests in 2014.
Street stalls are common in the Mong Kok area year-round, but particularly during the New Year holiday, where they are popular with locals for selling traditional new year snacks.
The BBC's Juliana Liu in Hong Kong says officials usually turn a blind eye to the hawkers' lack of official permits, but this year decided to crack down.
Ahead of the clearance operation, hundreds of people had gathered in the area to defend the hawkers.
Police said the vendors and activists were told to leave but ignored the warnings.
Clashes then broke out in the early hours, and carried on past dawn. But the scene was quiet by Tuesday morning.
Among the protesters were reportedly some "localist" - anti-Beijing - groups.
Baggio Leung, leader of the Youngspiration political party, told the BBC he and 10 other party members went to protest. The group said they were defending local culture.
One of them was arrested, Mr Leung said.
Cmdr Yau Siu-kei blamed "radical elements". The police had "no choice" but to fire warning shots to protect their colleagues, the South China Morning Post quoted him as saying.
The unrest was widely referenced on social media, where it was dubbed #fishballrevolution after one of the food delicacies sold by the hawkers.
(BBC)
