Hong Kong police said Monday they had "no other choice" after unleashing pepper spray and baton charges at students who tried to storm government headquarters overnight, in some of the worst violence since the pro-democracy protests began.
With demonstrations now in their third month, tensions soared after police beat back demonstrators who had surged onto a main road outside the government complex shouting: "Surround the headquarters. Paralyse the government."
"In a situation where they had no other choice, police used a minimal amount of force including spraying water, pepper spray... and batons," senior superintendent Tsui Wai-hung said.
But protesters at the main Admiralty rally site Monday expressed their fury and despondency after a number were injured in the clashes.
"I feel angry but there's nothing we can do about it," said account clerk Justin Yan, 22.
"They are supposed to protect the citizens, not (hurt) us. We saw what they did, so we don't trust them any more."
Demonstrators now fear that police will try to clear Admiralty, where hundreds of tents block a multi-lane highway through the heart of the financial district.
Police clash with pro-democracy protestors in Hong Kong
But security minister Lai Tung-kwok said he would not "prematurely" reveal future government actions for the area.
He accused protesters of "systematically" charging the police cordon outside the government offices.
"Their actions go against peace and non-violence," he said.
Protesters have been staging mass sit-ins in Hong Kong since late September, demanding free leadership elections for the semi-autonomous Chinese city.
China's communist authorities insist candidates for the 2017 vote must be vetted by a loyalist committee, which the protesters say will ensure the election of a pro-Beijing stooge.
Tearful protesters were forced from the government site and roads were cleared for traffic before morning rush hour Monday, but government offices remained closed with the de facto parliament suspended Monday morning.
Emotions were running high, with clashes between police and protesters at a shopping arcade near the Admiralty site, with at least one person stretchered away, according to an AFP reporter at the scene.
In chaotic scenes overnight, hundreds of protesters wearing helmets and wielding umbrellas spilled into a major road outside the office of Chief Executive Leung Chun-ying.
Police said they had made 40 arrests overnight and 11 officers had been injured.
Several protesters were injured in the overnight clashes. One was seen led away by police with a bloodied face, while others were tended to by first-aid volunteers after being fired at with pepper spray.
Protesters wore builders' hard hats and used umbrellas -- which have come to symbolise the pro-democracy movement -- to shield themselves from the pepper spray.
Police had to dodge helmets and bottles that were lobbed through the air. One officer was carted into the back of an ambulance on a stretcher.
"This is a long-awaited escalation of action. It should have happened ages ago," protester Kelvin Lau told AFP.
The protests drew tens of thousands of people at times during their first weeks, but the numbers have dwindled as the movement's leaders struggle to keep up momentum.
Frustrations have grown amongst the demonstrators as Beijing refuses to budge on the vetting of candidates, while support has waned among residents grown weary of the transport disruption.
Police cleared a protest site in working-class Mongkok last week, making more than 140 arrests, but sporadic scuffles have continued there between police and crowds of angry demonstrators.
A smaller camp blocks another busy road in the shopping district of Causeway Bay.
A British colony until 1997, Hong Kong enjoys civil liberties not seen on the Chinese mainland, including freedom of speech and the right to protest.
But fears have been growing that these freedoms are being eroded.