Officers used pepper spray and batons to beat back activists as they tried to reoccupy a busy main road in the bustling Mongkok district, which has been home to a protest camp for nearly three weeks, an AFP reporter on the scene saw.
"We want to take back this spot because it's what we had," said Gary Yip, a 17-year-old high school student.
It is the third consecutive night that violence has broken out after a fortnight of comparative calm -- a development that risks sinking only recently resurrected plans to hold talks between student leaders and the city's Beijing-backed authorities.
Protesters have held sit-ins at three major intersections causing significant disruption to a city usually known for its stability, and presenting Beijing with one of the most significant challenges to its authority since the 1989 Tiananmen protests.
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China has insisted that Leung's successor must be vetted by a loyalist committee before standing for election in 2017, a proposal protesters have dismissed as "fake democracy".
Mongkok had previously seen clashes between protesters and masked government loyalists earlier in the month.
Throughout today demonstrators managed to hold on to one side of a multi-lane road where the camp had been located. Police then struggled to maintain order as crowds of pro-democracy supporters began to swell during the evening.
Violence broke out around 8pm local time after several protesters tried to push through a police cordon.
An AFP reporter saw at least two protesters led away by police, some of whom donned helmets and riot shields. Paula Bronstein, a photographer with Getty news agency, was also detained by police during the clashes, two AFP reporters confirmed.
By late Friday the initial flurry of violence had subsided but police were facing off against thousands of protesters in a tense standoff.
Yesterday, the government had made a dramatic u-turn and announced a resumption of talks with the Hong Kong Federation of Students (HKFS), one of the groups leading the ongoing protests, after abruptly pulling out of discussions a week earlier.