Rights activists and residents say Syrian security forces backed by tanks today stormed the southern town of Daraa.
Daraa is the town where protests against President Bashar al-Assad's regime began last month.
A witness told Reuters he saw bodies in the street after hundreds of soldiers in armored vehicles and tanks poured into Daraa.
A resident told Al-Jazeera that tanks were shelling targets in the city.
Jordanian officials have confirmed that Syria today sealed off its border with Jordan. Daraa lies close to the border.
Activists and witnesses said Syrian security forces today stormed the Damascus suburb of Douma, shooting at civilians and arresting residents.
The reports could not be independently confirmed as most foreign correspondents have been expelled from Syria.
Rights groups say security forces have killed more than 350 civilians since the unrest in Syria began. A third of the victims were killed in the past three days.
The latest crackdown came despite the lifting of a nearly five-decades-old emergency law last week.
compiled from agency reports