Syria's state news agency said on Monday that security forces have arrested nearly 500 people and killed 10 others.
Witnesses in the flashpoint southern city, Daraa, said troops backed by armored vehicles roamed the streets in a continuing push to crush protests against President Bashar al-Assad.
Residents in Daraa said Syrian security forces detained males15-years-of-age and older and sealed off neighborhoods. A government spokesman said troops had killed 10 "terrorists."
Reports say troops are targeting prominent lawyers and activists in Daraa, which has been the center of Syria's six-week uprising.
Fuel, water, power and communications have been severely disrupted in Daraa for six days. Food is said to be scarce.
Rights groups say at least 560 civilians have been killed in the country-wide unrest in Syria.
Meanwhile, state media said Monday that the Interior Ministry issued a statement calling on people who committed illegal acts to turn themselves in by May 15.
It says those who go to authorities and turn in their weapons will be exempted from punishment.
Nearly all foreign media have been banned from Syria, making it almost impossible to independently confirm reports.
Some information for this report was provided by AP, AFP and Reuters.