BEIRUT -- Thousands of soldiers backed by tanks and snipers moved in before dawn to the city where Syria's anti-government uprising began, causing panic in the streets when they opened fire indiscriminately on civilians and went house to house rounding up suspected protesters. At least 11 people were killed and 14 others lay in the streets -- either dead or gravely wounded, witnesses said.

The military raids on the southern city of Daraa and at least two other areas suggested Syria is trying to impose military control on the centers of protests against President Bashar Assad, whose family has ruled Syria for four decades. Residents and human rights activists said the regime wants to terrify opponents and intimidate them from staging any more demonstrations.

The offensive was meticulously planned: Electricity, water and mobile phone services were cut. Security agents armed with guns and knives conducted house-to-house sweeps, neighborhoods were sectioned off and checkpoints were erected before the sun rose.

"They have snipers firing on everybody who is moving," a witness said over the telephone. "They aren't discriminating. There are snipers on the mosque. They are firing at everybody," he added, asking that his name not be used for fear of retribution.

The massive assault on Daraa appeared to be part of new strategy of crippling, pre-emptive strikes against any opposition to Assad, rather than reacting to demonstrations. Other crackdowns and arrest sweeps were reported on the outskirts of Damascus and the coastal town of Jableh -- bringing more international condemnation and threats of targeted sanctions by Washington.

Razan Zeitounia, a human rights activist in Damascus, said the widespread arrests appear to be an attempt to scare protesters and set an example for the rest of the country.