Hong Kong police attempted to shut down unlicensed food stalls along the junction of Shan Tung Road and Portland Street in Kowloon. Clashes erupted after dozens of local activists gathered to defend the vendors.
The unlicensed food stalls were set up for the Lunar New Year holiday. Officials usually turn a blind eye to the hawkers' lack of official permits, but this year decided to crack down.
The underlying tensions go deeper. Many "localist" groups, who want greater autonomy for Hong Kong, turned up to support the vendors, arguing that Hong Kong's identity is under threat. Trust between the public and the police has also declined in recent years. On social media the protest was dubbed #fishballrevolution, after one of the snacks on sale.
Hong Kong police will hold an inquiry to determine whether it was appropriate for an officer to fire two warning shots during unrest in Mong Kok.
Two handgun shots were fired into the air as hundreds of people clashed with police on Monday night.
The unrest began when officials began an operation to clear out unlicensed street food stalls.
More than 90 people, mostly police officers and reporters, were injured and dozens of people were arrested.
Protesters threw bricks and bottles at police, who were using batons and pepper spray.
Despite the attempted crackdown, food stalls were operating as usual again on Tuesday evening.