Fires burn in the streets as anti-government protesters clash with police on Feb. 18, 2014, in Kiev, Ukraine.

At Least 13 Dead in Ukraine Violence

Law enforcement officers, protesters are among the casualties.

Fires burn in the streets as anti-government protesters clash with police on Feb. 18, 2014, in Kiev, Ukraine.

Violent clashes have erupted in the city of Kiev this evening during anti-government protests, with at least 13 people dead so far including two policemen.

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Peaceful protests in the Ukrainian capital of Kiev once again decayed into a violent standoff between police and opposition members Tuesday. 

At least 13 people are dead with countless others injured, The Associated Press reported. Both law enforcement officers and protesters are among the wounded and the dead.

"Three bodies of our supporters are in the building. Another seven are close to dying (because of wounds)," opposition lawmaker Lesya Orobets said on her Facebook page, Reuters reported.

According to the BBC, Tuesday’s protest began with thousands of demonstrators attempting to march on the parliament building grounds in protests that encouraged the government to address constitutional reform. The march, however, was impeded by police officers. Things fell apart after the initial confrontation, BBC foreign correspondent David Stern reported.

Protesters and police clashed in multiple locations with smoke bombs, stun grenades and rubber bullets.

Government security authorities and the internal affairs ministry announced they would "use all the possible methods" to end the protests, the BBC reported. Vitaly Klitschko, an opposition leader, encouraged women and children to leave protest areas because he could not "exclude the possibility of use of force" against them and other protesters. 

[READ: Putin Adviser Threatens to Intervene in Ukraine]

NATO Secretary-General Anders Fogh Rasmussen asked both sides to avoid the use of violence at all costs. U.S. and European nations also discouraged the use of force, Reuters reported.

The U.S.' National Security Council said it was "appalled by the violence" and urged President Viktor Yanukovych to "immediately de-escalate the situation and end the confrontation," the BBC reported.

Ukraine had been making progress toward a peaceful resolution to the political crisis that has plagued Kiev ever since protests broke out in November. An amnesty bill recently released almost all protesters arrested since the upheaval began, prompting protesters to pull back from city hall and other streets they had been occupying, The Washington Post reported. Parliament also was scheduled to address constitutional changes that would take power from the president and give parliament more power.

However, opposition members said the measure had been blocked by Yanukovych.

[ALSO: Radicals a Wild Card in Ukraine's Protests]

"I think Yanukovych showed he would stick firmly by his position in talks [with the opposition], he would not make excessive concessions, he would fight the radicals who are getting stronger in the opposition … and that the [new] prime minister would not be a member of the opposition," said political analyst and former Kremlin adviser Gleb Pavlovsky, according to Reuters.

A possible sign of Yanukovych’s refusal to cooperate peacefully occurred Monday when Russia gave Ukraine $2 billion of a promised $15 billion cash stimulus. Some say this is a sign of Russia’s confidence in Yanukovych’s ability to end the crisis.

"I think Russia received some kind of assurances from the Kiev leadership that were satisfactory,” Pavlovsky said of Russia’s decision to give Ukraine the aid.