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Mortars reportedly kill 21 at refugee camp in Syrian capital

Activists report mortars hitting a Palestinian refugee camp in the Syrian capital. Meanwhile, Turkey has been holding military drills along its border with Syria. NBCNews.com's Dara Brown reports.

Updated at 11:19 a.m. ET: Mortars rained down on a crowded marketplace in a Palestinian refugee camp in the Syrian capital, killing 21 people as regime forces and rebels clashed on the southern outskirts of Damascus, activists said Friday.

With the civil war in Syria getting increasingly vicious, chances for a diplomatic solution to the 17-month-old conflict were fading after the resignation Thursday of Kofi Annan, the U.N.-Arab League envoy to Syria. Annan cited divisions within the Security Council preventing a united approach to stop the fighting.

The developments came as the U.N. General Assembly prepared to denounce President Bashar Assad's regime for unleashing tanks, artillery, helicopters and warplanes on the people of Aleppo and Damascus, its two largest cities. The resolution was also to demand that Syria keep its chemical and biological weapons warehoused and under strict control.

The attack on Yarmouk camp came as the government battled rebel fighters in the nearby Damascus suburb of Tadamon on Thursday evening. Clashes there continued on Friday and sounds of explosions from the neighborhood could be heard as far as the mostly deserted Damascus downtown, with plumes of smoke seen rising into the sky.

The U.N. agency running Palestinian camps confirmed that at least 20 people had died in the shelling of Yarmouk. The Britain-based Syria Observatory for Human Rights, which first reported the deaths, said the mortars hit as shoppers were buying food for the evening meal. The activists with the group would not speculate on who was firing.

"We don't know where the mortars came from, whether they were from the Syrian regime or not the Syrian regime," said Rami Abdul Rahman, director of the Observatory.

The state news agency blamed the bombardment on "terrorist mercenaries" — a term the government uses for rebel fighters — and said they had been chased away by security forces.

Kofi Annan quits role as UN's Syria envoy

In villages across Syria there is great concern for the city of Aleppo, where the violence seen in the last few days could be nothing compared to what's coming. NBC's Richard Engel reports.

The incident highlights the precarious situation of not just Palestinian refugees but all civilians in Syria who are increasingly getting caught in the crossfire of this bloody uprising that has claimed 19,000 lives since it erupted in March 2011. Every day hundreds of civilians are uprooted by the violence, according to the United Nations, which estimates that 1.5 million people have been force to abandon their homes but remain in the country.

Government troops have in the past attacked the camp, home to nearly 150,000 Palestinians and their descendants driven from their homes by the war surrounding Israel's 1948 creation. Palestinian refugees in Syria have tried to stay out of the 17-month old uprising, but with Yarmouk nestled among neighborhoods sympathetic to the rebels, its residents were eventually drawn into the fighting.

The situation of the Palestinian refugees is particularly sensitive because Syria has long cast itself as the principal champion in the Arab world of the Palestinian struggle against Israel. Palestinian President Mahmoud Abbas, whose government has a strict policy of neutrality regarding the Syrian conflict, condemned the Yarmouk attack.

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As the fighting intensifies in Aleppo, Syria's largest city, rebel forces say they need strategy guidance in addition to medical supplies. Their goal, they say, is to win the war instead of simply carrying out random attacks against the Syrian army. NBC's Andrea Mitchell reports.

Syria's civil war, which had spread across much of the country, only came to the capital and northeastern city of Aleppo, Syria's main commercial hub, in July.

Turkey: Brigadier-general among defectors
Meanwhile, about 1,000 Syrians, including a defecting brigadier-general, have fled to Turkey in the past 24 hours to escape intensifying violence, a Turkish official told Reuters on Friday. 

Elsewhere, the Russian Defense Ministry denied  that it plans to send naval vessels to the Syrian port of Tartus, the state-owned RIA news agency said.

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People resisting the army of President Bashar Assad in northern Syria cope with loss and prepare for fighting.

It dismissed reports, attributed by Russian news agencies to a source in the general staff, that Moscow was sending three large landing ships with marines aboard.

Security Council deadlock
Washington, U.N. diplomats say, has been convinced that the Security Council cannot play a meaningful role in the crisis since Russia and China first vetoed a Western- and Arab-backed resolution in October. Both countries have cast a double-veto three times to kill resolutions that could have opened the door to sanctions, or even military intervention.

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Moscow and Beijing have frequently complained about Western and Arab backing for the insurgents, saying pressure should be put on both sides to stop the violence.

That is partly why the General Assembly has taken up the resolution, but the resignation of joint U.N.-Arab League representative Annan after his peace proposals failed threatened to overshadow the developments in New York.

Before Syrian reinforcement troops can reach Aleppo, the nation's largest city and commercial capital, they are being attacked by rebel forces in Arihah, a city situated on a key route. NBC's Richard Engel reports.

Annan's peace plan was supposed to resolve Syria's conflict with an immediate halt to the violence, withdrawal of heavy weapons and military forces from built-up areas, access for humanitarian aid and journalists, and a political transition.

But Annan's mission looked irrelevant as fighting intensified in Damascus, Aleppo and elsewhere. 

Annan blamed "finger-pointing and name-calling" at the Security Council for his decision to quit but suggested his successor may have better luck.

Russia, the United States, Britain and France began blaming one another over who was responsible for Annan's sudden announcement he would depart. One senior council diplomat said it was now time to acknowledge the "utter irrelevance of an impotent Security Council" on Syria, Reuters reported.

Russia said it would not back Friday's resolution because it was unbalanced and would encourage rebels to keep fighting.

The anti-Syria resolution was expected to easily pass Friday in the 193-member General Assembly after its Arab sponsors de-fanged two key provisions in the original draft — a demand that Assad resign, and a call for other nations to place sanctions on Syria over its civil war.

NBC News staff, Reuters and The Associated Press contributed to this report.

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