Police said Monday that officer fired tear gas against protesters in Hong Kong overnight, ending a lull in what have become regular clashes between riot squads and demonstrators.

Police said they fired the choking gas after unrest erupted Sunday night in the Mongkok district of Kowloon.

Protesters threw bricks at officers and tossed traffic cones at a police vehicle, police said. They also set fires, blocked roads and smashed traffic lights with hammers.

Attendees hold cards listing four of their five demands during a six months anniversary memorial for a man who fell to his death while hanging a protest banner against an extradition bill on Sunday, Dec. 15, 2019 in Hong Kong. (AP PhotoMark Schiefelbein)

Attendees hold cards listing four of their five demands during a six months anniversary memorial for a man who fell to his death while hanging a protest banner against an extradition bill on Sunday, Dec. 15, 2019 in Hong Kong. (AP PhotoMark Schiefelbein)

Video footage showed truncheon-wielding riot officers squirting pepper spray in the direction of journalists and ganging up on a man, beating and manhandling him.

The violence and scattered confrontations in shopping malls earlier Sunday, where police also squirted pepper spray and made several arrests, ended what had been a lull of a couple of weeks in clashes between police and protesters.

Hong Kong's protest movement erupted in June against now-scrapped legislation that would have allowed criminal suspects to be extradited for trial in Communist Party-controlled courts in mainland China. It has snowballed into a full-blow challenge to the government and Communist leaders in Beijing, with an array of demands, including that Hong Kong's leader and legislators all be fully elected.

In this image made from video, a masked protester breaks glass barrier at a shopping mall in Sha Tin district in Hong Kong, Sunday, Dec. 15, 2019. Protesters were seen destroying some pro-China shops inside the mall, what led to minor scuffles with riot police and resulted in several arrests on Sunday.(AP Photo)

In this image made from video, a masked protester breaks glass barrier at a shopping mall in Sha Tin district in Hong Kong, Sunday, Dec. 15, 2019. Protesters were seen destroying some pro-China shops inside the mall, what led to minor scuffles with riot police and resulted in several arrests on Sunday.(AP Photo)