HONG KONG - Baton-wielding Hong Kong police fired warning shots and pepper spray early Tuesday after a riot erupted when officials tried to shift illegal hawkers, the worst clashes since mass pro-democracy protests in 2014.
Police said nearly 90 officers were injured by broken glass or hard objects, while dozens of protesters were also hurt in the Chinese New Year clash.
Footage showed protesters levering up bricks from pavements in the busy Mongkok district, charging police lines with homemade shields and setting rubbish on fire in the middle of the road.
One officer was seen pointing his gun at crowds who hurled bricks, bottles and pieces of wooden pallets at police.
Police fired at least two warning shots in the air, multiple news outlets reported, a very rare occurrence in the semi-autonomous southern Chinese city.
Police Commissioner Stephen Lo defended the officer who fired the warning revolver shots, saying rioters were continuously attacking his already injured colleague.
"With no alternative, his police colleague used his firearm in accordance with the use of force principles to prevent his fellow colleague from being further attacked," Lo said, adding there would be a full investigation.
Police said 54 protesters aged between 15-70 were arrested for assaulting police, resisting arrest and disorderly conduct in a public place, among others offences.
"We will consider charging the arrested persons for participating in a riot," Lo said. This carries a sentence of up to 10 years in prison.
Social media has dubbed the street battles that erupted after officials tried to move illegal food hawkers as the "fishball revolution".
Demonstrators, including members of radical "localist" groups which stress Hong Kong's separate identity from the mainland, tried to defend the hawkers whom they say add to the festive atmosphere.
Reports said one of those arrested was Edward Leung, a "localist" candidate for an upcoming by-election on February 28.
Hong Kong leader Leung Chun-ying said the government "strongly condemns such violent acts".
"There was a riot in Mongkok in the early hours of today," the chief executive told reporters. "A few hundred mobs attacked police officers and media." Footage from Cable Television News showed police and protesters still in a stand-off at daybreak while the city's subway operator the MTR closed Mongkok station.
It later reopened and the district was quiet later in the day.
At least four journalists were injured, one of which was on the head by a brick thrown by rioters, the Hong Kong Journalists Association said in a statement on its Facebook page.
TVB news footage showed protesters harassing and attacking their cameraman who sustained injuries to his hand.
The so-called "localists" seek to severely restrict Beijing's influence in the city. Some even want an independent Hong Kong.
The clashes come at a time when residents are on edge over concerns the city's freedoms are being eroded by China, which resumed sovereignty in 1997.
There is particular concern at the fate of five Hong Kong based-booksellers believed to be detained in mainland China after disappearing last year from various places.
One of them vanished from Hong Kong, fuelling concern he had been abducted by mainland law enforcers who have no right to operate in the city.
Mongkok on the city's Kowloon peninsula was the scene of some of the worst violence during the 79-day "Occupy" pro-democracy street protests in late 2014.
The mass rallies seeking fully free leadership elections in the city blocked some major streets for more than two months.