More than 260 people were reportedly killed on Saturday morning in Syria's Homs by security forces in one of the bloodiest attacks since the uprising against Bashar-al-Assad started.
Though the government denied any hand in the violence, there was a war-like atmosphere in the city, according to civil rights groups.
Residents said Syrian forces began shelling the Khalidiya neighbourhood at around 8 p.m. (6 p.m. British time) on Friday using artillery and mortars. They said at least 36 houses were completely destroyed with families inside, adds Reuters.
"We were sitting inside our house when we started hearing the shelling. We felt shells were falling on our heads," said Waleed, a resident of Khalidiya.
It is not possible to verify activist or state media reports as Syria restricts independent media access.
As news of the violence spread, crowds of Syrians stormed the Syrian embassies in Cairo and Kuwait in protest, and demonstrators rallied outside Syrian missions in Britain, Germany, Greece and the United States.
It was not immediately clear what had prompted Syrian forces to launch such an intense bombardment, just as diplomats at the Security Council were discussing the draft resolution supporting the Arab League demand for Assad to step aside.
Some Syrian activists said the violence was triggered by a wave of army defections in Homs, a stronghold of protests and armed insurgents who Assad has vowed to crush.
"The death toll is now at least 217 people killed in Homs, 138 of them killed in the Khalidiya district," Rami Abdulrahman, head of the British-based Syrian Observatory for Human Rights, told Reuters, citing witnesses.
"Syrian forces are shelling the district with mortars from several locations, some buildings are on fire. There are also buildings which got destroyed."
A Syrian activist said Assad forces bombarded Khalidiya, a key anti-Assad district, to scare other rebel neighbourhoods. "It does not seem that they get it. Even if they kill 10 million of us, the people will not stop until we topple him."
The opposition Syrian National Council said 260 civilians were killed, describing it as "one of the most horrific massacres since the beginning of the uprising in Syria".
Video footage on the Internet showed at least eight bodies assembled in a room, one of them with the top half of its head blown off. A voice on the video said the bombardment was continuing as the footage was filmed.
One activist said residents were using primitive tools to rescue the people. They feared many were buried under rubble.
"We are not getting any help, there are no ambulances or anything. We are removing the people with our own hands," he said, adding there were only two field hospitals treating the wounded. Each one had a capacity to deal with 30 people, but he estimated the total number of wounded at 500.
"We have dug out at least 100 bodies so far, they are placed in the two mosques."
At the United Nations, the Security Council was due to meet at 10 a.m. (1500 GMT) to vote on the Western-Arab draft endorsing an Arab League plan calling for Assad to resign.
"As a tyrant in Damascus brutalizes his own people, America and Europe stand shoulder to shoulder. We are united, alongside the Arab League, in demanding an end to the bloodshed and a democratic future for Syria," U.S. Secretary of State Hillary Clinton said at a security conference in Munich.
"And we are hopeful that...the Security Council will express the will of the international community."
But Russia has balked at any language that would open to door to "regime change" in Syria, its crucial Middle East ally where Moscow operates a naval base.
"If they want another scandal for themselves in the Security Council, then we probably cannot stop them," Lavrov said in comments reported by the Itar-Tass agency.
He said he hoped the draft would not come to a vote without changes "because our amendments to this draft are well-known".
Clinton and Lavrov were scheduled to meet at 1030 GMT on Saturday on the sidelines of the Munich conference for talks expected to focus on Syria.
In Cairo, a crowd stormed the Syrian embassy smashing furniture and setting fire to parts of the building in protest over the Homs bloodshed.
The gate of the embassy was broken and furniture was smashed on the second floor of the building, a Reuters witness said. It was the second attack on the mission in a week.
In London, more than 100 Syrians hurled stones at the Syrian embassy, smashing windows and shouting slogans, and five people were arrested after trying to break in, according to TV reports.
In Washington, about 50 people took part in a nighttime rally outside Syria's embassy, chanting "Down with Assad". Syrians also demonstrated at embassies in Kuwait and Athens.
Some carried signs including one that juxtaposed pictures of Assad and Adolf Hitler. "We want to show solidarity with the people in Syria being killed every day," said Mohammad Kousha, a Syrian living in Washington.
In the cities of Hama and Idlib, activists said hundreds of people took to the streets in solidarity. They chanted in Idlib: "Homs is bombarded, and you are still sleeping?"
Check out the pictures of the early morning violence in Syria on Saturday: