By Karine Barzegar, and Sumi Somaskanda

"It's a horrific and horrible massacre," said Saffour, who says contacts tell him that dozens of people lay dead in Baba Amr, including women and children.

WADI KHALED, Lebanon – As Western nations increasingly push to end the violence in Syria, dissidents on Tuesday said the killings are escalating in the city of Homs — a flash point for the uprising — where residents are fighting furiously to prevent their own annihilation.

Troops under President Bashar Assad continued on Tuesday to shell the Baba Amr district of Homs, Syria’s third-largest city and an area that has been under siege for months. More than 300 people are believed to have died in Homs last weekend, said Walid Saffour, president of the Syrian Human Rights Committee in London.

“It’s a horrific and horrible massacre,” said Saffour, who says contacts tell him that dozens of people lay dead in Baba Amr, including women and children. “They shelled peaceful people in their houses. People are being killed and there is no remedy, no treatment, no ambulances, no hospitals to treat the wounded people at all.”

Since the uprising in Syria began 11 months ago, nearly 6,000 people have died, according to the United Nations, and the violence has escalated in the past few weeks as Assad seeks to crush what was largely a peaceful protest movement.

“I just don’t see a light at the end of the tunnel,” said Fawaz Gerges, director of the Middle East Center at the London School of Economics. “I think both sides have made up their minds. There is nothing to compromise about — they’re going for broke.”

Russia’s foreign minister, Sergey Lavrov, arrived in Damascus on Tuesday and urged Assad to move ahead with political changes to address opponents who demand Assad’s resignation. Lavrov was met by thousands of Assad supporters waving Russian flags and praising his country for blocking attempts to enact sanctions against Syria’s government at the U.N.

Meanwhile, the military onslaught continued against Homs and civilians in other cities, activists said. Syria has blocked access to trouble spots and prevented independent reporting.

Hervin Ose, a member of the minority Kurdish Future Movement Party in Syria, said she has witnessed brutal force by government troops in her travels through the country over the past few weeks and months.

“(The government) declared a war against the people in Syria,” she said from Damascus. “This regime has become a cancer.”

Many citizens are fleeing in waves across the border to Turkey or Lebanon, to friends, family or refugee settlements. But these escape routes are monitored by Syrian security forces.

“It’s more difficult to cross the border because of the mines installed and because of the heavy presence of the Syrian army,” said Alain Gharafi, a field coordinator in Lebanon for the Office of the United Nations High Commissioner for Refugees. “Still, these are mountainous regions, and people manage to cross at night and the border is not heavily guarded on the Lebanese side.”

Hundreds of Syrian dissidents in Lebanon have boosted efforts to help the opposition from Beirut and Tripoli and the border village of Wadi Khaled in northern Lebanon. They say they are in constant touch with activists inside Syria, and smuggle medicine, satellite phones, cameras and weapons into Syria. They help refugees and the injured get out, according to groups such as Al-Bashaer in Tripoli.

“At the beginning, there were just a few, a first wave of refugees who settled down at the border,” group spokesman Wassim Bashir said. “Then the events escalated and bigger waves of refugees came and stayed longer than planned.”

“Assad has made it very clear that he is going to resolve this conflict once and for all,” Gerges said. “And what he means by resolve is, he is going to crush the opposition.”

The global tensions have placed Syria in the midst of a larger tug of war pitting the U.S. and its allies against Russia, China and Iran. And that, activists say, has only exacerbated the crisis.

“If (the Syrian government) didn’t have that support, they wouldn’t dare to go that far in killing and suppressing the uprising and demonstrations,” said Hozan Ibrahim, a spokesman for the Local Coordination Committees of Syria.

He added, however, that “the uprising won’t stop. … More defecting soldiers will join the Free Syrian Army (of military defectors). That will make us stronger and weaken the regime day by day.”

Saffour said the international community has promised too little too late, leaving the Syrian people alone in their fight for freedom.

The West “can stop Assad by imposing the no-fly zone, by securing safe havens in some parts of Syria, especially in the north and near Turkey and Lebanon,” he said. “They can do a lot of things, but there is no international will so far .”

Others say the conflict will rage for some time because Assad has support in many parts of the country. Some of Syria’s most significant minority groups, such as Christians and Alawites, have stood behind Assad, for fear of what fragmented opposition forces would bring to power.

“We’re not just talking about a small circle, we’re talking about a critical social base,” Gerges said. “We’re talking 25 to 40% — that’s a lot of people.”

Contributing: Barzegar reported from Lebanon; Somaskanda reported from Berlin