By Ivan Watson, Vivian Kam and Wilfred Chan, CNN
December 1, 2014 — Updated 0654 GMT (1454 HKT)
Hong Kong (CNN) — Police clashed with activists at the main Hong Kong pro-democracy protest site Monday morning after a violent nighttime standoff when protesters surrounded government headquarters in the city’s Admiralty district.
Authorities removed some tents and barricades at the main protest site before withdrawing. The site is currently calm.
Protesters, following student leaders’ calls to escalate their civil disobedience movement, surrounded the government complex Sunday night and charged onto Lung Wo Road, a major east-west route next to the headquarters. Police used batons and pepper spray to push back demonstrators.
Police and protesters were seen injured in the clashes, with protesters seen receiving first aid treatment from fellow activists, and police carried away on gurneys.
The standoff continued Monday morning as police moved in on the main Hong Kong pro-democracy protest site, cutting down banners on a pedestrian overpass above thousands of tents inside the “democracy village” in Hong Kong’s Admiralty district.
Before dawn Monday, at least 40 arrests had been made in Admiralty, according to the Hong Kong Police. A further 12 people were also arrested in Mong Kok.
The Central Government Office was closed on Monday morning but later re-opened.
The government said it condemned “violent radicals,” saying they had “provoked and verbally abused police officers” and encouraged others to charge police lines.
“We do not have any plan”
The current police operation is the boldest move authorities have made on the main protest site in nearly two months.
Protesters seemed at a loss for how to respond, with arguments breaking out between student leaders and protesters even as police moved in.
Winnie Ng, a demonstrator, told CNN “We do not have any plan.”
This morning, a tweet from student leader group Hong Kong Federation of Students read “We need your support in Admiralty right now.”
The tense standoff came at the end of a dramatic week in which Hong Kong authorities moved to dismantle protest camps in the city’s working-class Mong Kok district, arresting dozens and drawing accusations of brutality in the process.
Protesters want their occupations to pressure the Chinese government into giving Hong Kong open elections for its next leader in 2017. So far, officials have shown no willingness to give into protesters’ demands.
The protests have drawn widespread international attention, although the Chinese government has rebutted any efforts by outside countries to “interfere.”
On Sunday Sir Richard Ottoway, who chairs the British parliament’s Foreign Affairs Committee, said he and other lawmakers had been barred by China from making a planned trip to Hong Kong to assess the political situation.
“The Chinese government are acting in an overtly confrontational manner in refusing us access to do our job,” he said.
Michael Pearson wrote from Atlanta. Ivan Watson and Vivian Kam reported from Hong Kong. CNN’s Anjali Tsui and Felicia Wong also contributed to this report.