Story highlights Video posted Friday shows armed men exulting in a room full of bodies

Activist says the video was shot in March near the northern town of Jisr al Shugur

In Qubeir, U.N. observers smell "a strong stench of burnt flesh"

That village was the site of a massacre, activists say, that claimed 78 lives

At least 20 people were killed and dozens wounded early Saturday from sporadic shelling in the southern Syrian city of Daraa, an opposition group said.

Women and children were among the casualties from the ongoing clashes that were taking place between regime forces and rebel fighters in the area, said the group, Local Coordination Committees of Syria.

"Several doctors have been detained to prevent them from aiding the wounded amid a state of panic among residents due to the abuses regime forces are committing against the people there," it added.

The LCC reported 65 killed across Syria on Friday, when United Nations observers made it to the site of what activists have called a massacre on Wednesday in the village of Qubeir, near Hama.

Their arrival at 3:30 p.m. had been delayed by a day after government forces and civilians in the area blocked their approach to the village on Thursday, said Sausan Ghosheh, spokeswoman with the U.N. Supervision Mission in Syria.

Once in Qubeir on Friday, the U.N. team was shown burned houses and graves of the victims in the village, activist Mousab Alhamadee said.

The village "was empty of its own residents and thus the observers were not able to talk to anyone who witnessed Wednesday's horrific tragedy," said Ghosheh.

Tracks left by armored fighting vehicles were visible in the vicinity; some homes were damaged by rockets, grenades and a range of other weapons, she said.

"Inside some of the houses, the walls and floors were splatted with blood. Fire was still burning outside houses and there was a strong stench of burnt flesh in the air."

She said that the circumstances surrounding this crime "are still unclear. The number and names of those killed are still not confirmed."

At least 78 people were killed in Qubeir, according to the opposition network Local Coordination Committees of Syria.

A video of the carnage was posted on YouTube. CNN could not independently verify its authenticity.

Opposition activists said government forces shelled Qubeir for an hour before militias on foot turned AK-47 rifles on people, some at close range, or slashed them with knives. Some residents suspected the Shabiha, armed gangs that work as freelancers for the government.

The Syrian government has blamed terrorists for the attack in Qubeir and said nine people were killed.

Another amateur video posted Friday shows armed men wearing military uniforms cheering and celebrating in a room containing about a dozen bodies. The military men can be seen dragging some of the bodies, most of which have their hands tied behind their backs and appear to have been shot. Most of the military are not wearing regular army boots, which may indicate that they belong to a government militia or Shabiha.

The video was purportedly shot on a farm near the northern town of Jisr al Shugur in Idlib province.

An activist, who cited security concerns in asking not to be identified, told CNN that the incident took place on March 10 in the village of al Hamama, about 17 km (11 miles) northeast of Jisr al Shugur near the Turkish border. He told CNN the bodies were of activists who had taken refuge on the farm, where they were killed in an ambush by government militias.

The man said some of the victims were his friends and that he witnessed the aftermath.

A local activist group in Jisr al Shugur described the incident in a Facebook post that listed 13 names of the people who it said were killed.

Such images have sparked widespread condemnation of Syrian President Bashar al-Assad, who international leaders accuse of having failed to comply with a peace plan brokered by Kofi Annan, a special envoy on Syria for the United Nations and the Arab League.

Annan met Friday with U.S. Secretary of State Hillary Clinton after a marathon session Thursday on Syria in the U.N. General Assembly.

Al-Assad is accused of engineering a bloody crackdown to suppress a 15-month anti-government uprising.

CNN cannot independently confirm reports from within Syria because the government limits access by international journalists.

Also Friday, China condemned the ongoing violence in Syria, while in many parts of the country, warplanes flew overhead and the sounds of explosions and gunfire echoed as protesters gathered for another round of demonstrations.

Using some of the strongest language to emerge to date from Beijing on the violence in Syria, Foreign Ministry spokesman Liu Weimin called for an immediate end to the violence.

"We strongly condemn the recent brutality on women and children," he said. "We call for a punishment of the murderer."

Though Liu said China "holds an open attitude towards any solution that would help ease the situation in Syria and possibly push forward a political solution," there was no indication that Beijing had changed its position on outside intervention in Syria.

On Thursday, Chinese President Hu Jintao signed a joint declaration with Russia and four Central Asian nations rejecting armed intervention or efforts to topple al-Assad's regime.

Instead, they reiterated support for Annan's mediation efforts and called on all parties in the conflict to stop violence and engage in dialogue.

Frustrated world leaders warned that Syria is engaging in crimes against humanity and drifting closer to civil war.

"How many more times have we to condemn them, and how many ways must we say we are outraged?" U.N. Secretary-General Ban Ki-moon asked Thursday after 10 hours of talks on Syria. "The danger of full-scale civil war is imminent and real, with catastrophic consequences for Syria and the region."

Large demonstrations took place Friday in Damascus, Aleppo, Idlib and Deir Ezzor as government forces fired on protesters with bullets and tear gas, set fire to cars and killed at least four, the LCC said.

The state-run news agency, SANA, reported an attack on oil installations in Deir Ezzor that left one soldier dead, as well the deaths of two police officers and three civilians in a car bomb explosion in Idlib.

In April, Annan brokered a peace plan in Syria that included calls for warring sides to silence their guns and lay down their weapons. But provisions in the plan have not been met, and the most visible evidence is the continuing bloodshed.

Opposition groups estimate that 12,000 to at least 14,000 people have been killed in the Syrian uprising. Tens of thousands of others have been displaced.

A June 20 summit in Mexico will include discussions on how to proceed, Ban said.