Thailand's Prime Minister Yingluck Shinawatra has told the country she will do anything to stop the violence but cannot accept the demands of protesters.
However, the violence on the streets of the capital, Bangkok, appears to be getting worse.
"Anything I can do to make people happy, I am willing to do ... but as prime minister, what I can do must be under the constitution," Yingluck said in a televised address on Monday.
These were her first comments since violence erupted late on Saturday after weeks of peaceful protests.
"The armed forces will be neutral and I know they want to see the country in peace," Yingluck said, adding that her immediate aim was to restore "peace" to Bangkok's streets.
However, not long after she said she would open every door to end the crisis, her national security chief admitted that rubber bullets were being used against protesters.
Police used tear-gas and water cannons at the heavily guarded government headquarters on Monday to drive thousands of protesters back, as demonstrators hurled sticks, stones, bottles and other projectiles at security forces, manning barriers at the besieged complex.
A van carrying Al Jazeera's Scott Heidler and his crew was struck by gunfire, but no one was injured. It was unclear who opened fire.
Earlier on Monday, Al Jazeera Online's Robert Kennedy, reporting from Bangkok, said that a group of protesters about 200 metres away from the government office claimed live ammunition was fired earlier in the day, showing photos of a man with what looked like a gunshot wound to the thigh, and what looked like a bullet hole that had pierced a silver truck.
Thana Narkboonnam, 49, an anti-government protester, told Al Jazeera: "We want a revolution to be able to choose better representatives. This government is full of corruption, the political system needs to be entirely changed."
Loud periodic booms rang out as tear gas canisters were launched, Kennedy said, adding that he saw medics rush a wounded man on a stretcher into an ambulance with a wound to the right side of his torso.
Victory Day protests
The protesters had set Sunday as Victory Day to topple the government, but failed to achieve their goal of seizing the prime minister's office.
The UN closed its main office in Bangkok, dozens of schools stayed empty and many civil servants did not show up at work on Monday after the unrest that rippled around the key government buildings in the capital over the weekend.
In an e-mailed statement to its staff, the UN’s security department said that "there could be violence [on Monday] on a large scale… staff should avoid government offices'' and other protest locations.
|Thai PM Yingluck Shinawatra talks to Al Jazeera
Suthep Thaungsuban, the opposition protest leader, said on Sunday that he met Yingluck but insisted there were no negotiations to end the political crisis.
Suthep said he told Yingluck that the opposition would accept nothing less than her resignation and an appointed council taking over the government.
The protests were prompted by an amnesty bill, which opponents feared would have allowed Thaksin Shinawatra, Yingluck's brother and former prime minister, to return to the country.
Yingluck told Al Jazeera on Sunday that the government was no longer trying to pass the controversial bill that would have pardoned many people involved in corruption.
The latest conflict in Thailand has pitted Bangkok's urban population against the rural supporters of Shinawatras.
Political instability has plagued Thailand since the removal of Thaksin from his seat in a 2006 coup.
Two years later, anti-Thaksin protesters occupied Bangkok's two airports for a week after taking over the prime minister's office for three months.
Source: Al Jazeera and agencies