Clashes have broken out in the Mong Kok district of Hong Kong during a police operation to clear illegal food stalls.
The unrest erupted as food and hygiene inspectors tried to move the vendors away from a major junction in the early hours of Tuesday morning.
Angry vendors threw bricks and other missiles at police, who responded with batons and pepper spray.
One senior official said police had fired two warning shots and that 44 people, including police, were injured.
Yau Siu-kei, the acting district commander for Mong Kok, blamed “radical elements” for what he said was a riot.
“Because many rioters were attacking police with hard objects and seriously threatened their lives, there was no choice but to protect colleagues,” the South China Morning Post quoted him as saying.
In a statement, police said the vendors had ignored warnings to leave the area. Three men, aged 27 to 35, had been arrested for assaulting and obstructing officers, said the statement.
The clashes carried on into the morning.
It was the largest unrest in Hong Kong since the massive pro-democracy street protests in 2014.
Hong Kong is currently celebrating the Lunar New Year, which began on Monday and which the territory marks with three days of public holiday.
Street stalls selling souvenirs, food and drink are common and it is not uncommon for some to lack official permits.