Hong Kong's Lunar New Year celebration descended into chaos as protesters and police clashed over a street market selling fish balls and other local holiday delicacies.
The violence is the worst in Hong Kong since pro-democracy protests rocked the city in 2014, leaving a growing trust gap between the public and authorities.
Activists angered over authorities' attempts to crack down on the food hawkers in a crowded Kowloon neighbourhood held running battles with police into the early morning hours of Tuesday (local time).
Protesters pelted officers with bottles and pieces of rubbish. Some threw garbage cans, plastic safety barriers and wood from shipping pallets at them. They also set fires on the street.
At one point, a protester tried to tackle a traffic police officer from behind before both sides rush in to the melee in the middle of a busy street, according to footage shown by local news channel Cable TV. Moments later, another officer appeared to fire one or two warning shots into the air.
Hong Kong police said in a statement that the protesters had ignored their warnings to get off the street and shoved officers, who responded with batons and pepper spray.
Three men were arrested and three officers were injured and sent to hospital.
The unrest started when authorities tried to prevent unlicensed street food sellers from operating on Monday night in Mong Kok, a working-class district of the city.
The hawkers have become a local tradition during the Lunar New Year holiday but this year authorities tried to remove them.
The hawkers were backed by activists who objected to the crackdown over concerns that Hong Kong's local culture is disappearing as Beijing tightens its hold on the semiautonomous city.
The latest scuffles underscore how tensions remain unresolved more than a year after the end of pro-democracy protests that gripped the city.
Mong Kok, a popular and densely populated shopping and entertainment district, was one of the neighbourhoods where activists occupied streets for about 11 weeks in late 2014 to demand greater electoral freedom.