CAIRO -- Syrian army tanks shelled the old quarter of a city at the heart of the country's six-week-old uprising Sunday and rolled in more reinforcements to the area, which has been under siege for nearly a week, said an eyewitness.
Residents appeared to remain defiant: Unable to leave their homes, they chanted "God is Great!" to each other from their windows, infuriating security forces and raising each other's spirits.
"Our houses are close to each other, so even though we can't go outside, we stand by the windows and chant," said a Daraa resident, speaking to The Associated Press by satellite phone. "Our neighbors can hear us and they respond."
Daraa has been without water, fuel or electricity since Monday, when the regime sent in troops backed by tanks and snipers to crush protests seeking an end to President Bashar Assad's authoritarian rule.
Tanks and armored personal vehicles have cut off neighborhoods, and snipers nesting on rooftops throughout the city have kept residents pinned in their homes. Other areas of the country also have come under military control, but Daraa has faced the most serious stranglehold.
The death toll has soared to 535 nationwide from government forces firing on demonstrators -- action that has drawn international condemnation and U.S. financial penalties on top figures in his regime.
Tanks fired shells into the heart of Daraa's ancient Roman quarter Sunday, said a resident who lives on the outskirts of the city. He said he could identify the weaponry because he was a former soldier.
Men were forbidden to leave their homes but women were allowed out in the early morning to search for bread, he said, speaking on condition of anonymity for fear that Syrian forces would identify him.
The witness' accounts could not be independently verified. Syria has banned nearly all foreign media and restricted access to trouble spots, making it almost impossible to confirm the dramatic events shaking one of the most authoritarian regimes in the Arab world.
In addition to the military siege, security forces continued their arrest campaign of activists and suspected demonstrators, said Damascus-based activist Razan Zaitouneh, who is in hiding with her husband.
"They want to paralyze the (protest) movement," Zaitouneh said Sunday.
Zaitouneh said security forces arrested her husband's 20-year-old brother to pressure the couple to turn themselves in. She said the arrest happened on Saturday afternoon after the young man was checking on their house in Damascus.
"He called us saying they (security forces) are banging heavily on the door. He was terribly frightened and he said they would rip off the door," Zaitouneh said.
An hour later, Zaitouneh said the young man called them again, clearly shaken. "He said: come, I want to see you -- it was clear he was under pressure to talk to us," she said. They have not been able to contact the young man since.
On Saturday, Syrian troops killed four people while storming a mosque that became a focal point for protesters in Daraa, and security forces in Damascus kept dozens of women from marching on parliament to urge Assad to end his crackdown on the uprising.
The military raid on the Omari mosque in Daraa came a day after 65 people were killed -- most of them in Daraa, a southern city near the border with Jordan.
Friday was the second deadliest day since the uprising began in mid-March in Daraa, kicked off by the arrest of a group of teenagers who scrawled anti-government graffiti on a wall. The protest movement quickly spread nationwide and is now posing the gravest threat to the 40-year ruling dynasty of the Assad family.
The president has responded with overtures of reform coupled with a brutal crackdown -- although in the past week, the regime has intensified its attempts to crush the revolt by force.
On Saturday, Syrian Prime Minister Adel Safar said the government is preparing a "comprehensive plan for the aspired reforms" in the coming weeks "in response to the citizens' demands and needs."
But previous overtures have failed to dampen the protesters, who are now seeking Assad's ouster. The mounting death toll has served to embolden the movement, which at first appeared only to be demanding reforms.
Heaping further punishment on relatives of those killed Friday, they were told to hold small funerals with only family members invited, an activist said, in an apparent attempt to keep the services from turning into anti-Assad protests.
Similar orders were given last week, but most people did not follow them, said the activist, Ammar Qurabi, who heads the National Organization for Human Rights in Syria.
The Obama administration imposed financial penalties on three top Syrian officials, including Assad's brother, Maher, as well as Syria's intelligence agency and Iran's Revolutionary Guard over the crackdown.
The unrest in Syria -- one of the most repressive and tightly controlled countries in the Middle East -- has repercussions far beyond its borders because of the country's alliances with militant groups like Lebanon's Hezbollah and with Shiite powerhouse Iran.