The Obama administration is considering "targeted sanctions" against the Syrian government of President Bashar Assad in response to a violent crackdown on protesters, the White House said on Monday."The brutal violence used by the government of Syria against its people is completely deplorable," White House spokesman Tommy Vietor said. "The United States is pursuing a range of possible policy options, including targeted sanctions, to respond to the crackdown and make clear that this behavior is unacceptable."RELATED:Syrian forces kill 9 civilians, arrest leading AlawiteHuman Rights Watch calls on UN to probe Syria violenceA US official said earlier that the measures under consideration included a freeze on assets and a ban on US business dealings.The talk of US sanctions came as Syrian troops and tanks stormed Deraa on Monday, seeking to crush resistance in the city where a month-long uprising against the autocratic 11-year rule of Assad first erupted.A witness told Reuters he saw bodies in the street after hundreds of soldiers in armored vehicles poured into Deraa, a few miles from Syria's southern border with Jordan which officials said was sealed off. Various media reports quoted human rights activists as saying at least 25 people were killed in violence on Monday.Also Monday, Syria closed all its land border crossings with neighboring Jordan, Jordanian officials said, following the deployment of Syrian army tanks in the southern border city of Deraa. A spokesman in Damascus denied the closure, but photos of the sealed border were published in the world's media shortly after.A senior diplomat in the Jordanian capital confirmed that the two main Syrian crossings at Deraa and Nassib on the Syrian side were closed to traffic. An official told Reuters the "timing is related to what appears to be a major security operation that is taking place right now." A leading Syrian human rights campaigner said security forces, which also swept into the restive Damascus suburb of Douma, were waging "a savage war designed to annihilate Syria's democrats".Rights groups say security forces have killed more than 350 civilians since unrest broke out in Deraa on March 18. A third of the victims were shot in the past three days as the scale and breadth of a popular revolt against Assad grew.Assad lifted Syria's 48-year state of emergency on Thursday but activists say the violence the following day, when 100 people were killed during protests across the country, showed he was not serious about addressing calls for political freedom.Monday appeared to be the first time the authorities have sent tanks into population centers since the protests began.The raids on Deraa and Douma suggested that Assad, who assumed power when his father died in 2000 after ruling Syria with an iron fist for 30 years, was determined to crush the opposition by force.The witness in Deraa told Reuters he could see bodies lying in a main street near the Omari mosque after eight tanks and two armored vehicles deployed in the old quarter of the city."People are taking cover in homes. I could see two bodies near the mosque and no one was able to go out and drag them away," the witness said. Snipers were posted on government buildings, and security forces in army fatigues had been shooting at random at houses since the tanks moved in just after dawn prayers.Tanks at the main entry points to Deraa also shelled targets in the city, a resident named Mohsen told Al Jazeera, which showed a cloud of black smoke hanging over buildings. "People can't move from one street to another because of the shelling."