Symbol of protest, Syria LONDON - Arabstoday Army tanks continued to shell residential areas in the southern city of Deraa Tuesday.  Sources in Deraa told Al Arabiya that members of the Syrian army\'s 5th brigade had defected to join the protesters and were now engaged in fighting the security forces while  Damascus was accused of resorting to military force to crush dissent. After the Syrian army deployed in Deraa early on Monday, tanks were used to shell civilian buildings, sources told Amnesty International. \"By resorting to the use of artillery against its own people today, the Syrian government has shown its determination to crush the peaceful protests at virtually any cost, whatever the price in Syrians\' lives,\" said Malcolm Smart, Amnesty International\'s Middle East and North Africa Director. \"President Bashar al-Assad must call a stop to this now. He must pull back his army from Deraa immediately and ensure that basic services to the city are restored. Humanitarian assistance must be allowed to reach the victims of this latest totally unacceptable onslaught.\" All water and electricity services have been cut off to the town, which has been at the centre of protests that have swept the country since mid-March and was where the first protesters were killed by security forces. Amnesty International has received the names of 23 people who are reported to have died in today\'s attack on Dera\'a by the Syrian army, but the total number of dead is feared to be much higher. Many of the dead are said to have been killed by shelling. Government snipers are also reported to have been deployed and to have targeted those trying to assist wounded people lying in the streets, according to Amnesty International\'s sources. Some dead bodies were left lying in the streets near the \'Omari mosque and elsewhere as people were prevented from collecting them. The army was also believed to be using similar heavy-handed tactics in the Damascus suburb of al-Muadamiya and there were media reports of further killings of protesters in Douma. Amnesty International believes that at least 393 people have been killed by Syrian security forces since protests began five weeks ago. \"This is a government that seems to be running scared of its own people and their demands for political and other reform,\" said Malcolm Smart. \"The concessions offered by President al-Assad were too little, too late for the protesters, and now the government seems intent on reminding them of its true, repressive nature, in the hope that this will force them into submission. Yet this new brutality may simply serve to redouble the protesters\' determination to stand up and demand their rights.\" The United States has ordered embassy family members and some non-emergency personnel to leave Syria, citing the “uncertainty and volatility” of a crackdown on protesters there. The State Department’s directive early Tuesday, along with a travel warning telling US citizens to leave the country, followed another day of violent attacks on protesters by Syrian security forces.“The Department of State has ordered all eligible family members of US government employees as well as certain non-emergency personnel to depart Syria,” the statement said, according to Agence-France Press. “Embassy operations will continue to the extent possible under the constraints of an evolving security situation,” it said. “US citizens in Syria are advised to depart while commercial transportation is readily available,” the statement said. Some 390 people have been killed in security crackdowns in the country of 23 million people since the protests erupted, rights activists and witnesses told AFP. Washington has been analyzing what steps to take against Syria in response to the violence. It is considering targeted sanctions but has not called for President Bashar al-Assad to step down. Washington earlier Monday also defended the presence of an American ambassador in Damascus. The ambassador, who arrived in January 2011, was the first to fill the post in six years. Sanctions would mark a more assertive approach by the US President Barack Obama’s administration, which has been criticized by human rights groups for not doing more to curb Mr. Assad’s efforts to crush a month-long uprising against his autocratic 11-year rule. Mr. Obama’s response to the Syrian crisis has been limited compared to Washington’s role in a NATO-led air campaign against Libyan leader Muammar Qaddafi’s forces and its call for his ouster. President Obama spoke by phone with Turkish Prime Minister Tayyip Erdogan, and the White House later said they expressed deep concern about the violence in Syria, Reuters reported. “The leaders agreed that the Syrian government must end the use of violence now and promptly enact meaningful reforms that respect the democratic aspirations of Syrian citizens,” the White House said.Washington is mindful of its limited ability to influence Damascus, which is already under a set of US economic sanctions and is closely allied with Iran, a US foe. The Obama administration is also worried about stoking instability on US ally Israel’s borders and wants to avoid another military entanglement in the Muslim world, where it is involved in wars in Iraq and Afghanistan. President Assad lifted a 48-year state of emergency last Thursday but activists say violence the following day, when 100 protesters were killed, showed he was not serious about reform. Questions have been raised whether new US sanctions against Mr. Assad and his aides—such as the steps taken against Colonel Gaddafi and his loyalists—would have much tangible impact. Washington and other Western powers have been trying for two years to woo Mr. Assad away from Tehran and encourage the 46-year-old British-trained eye doctor to reach a peace deal with Israel, according to Reuters. Western sanctions could push Syria more tightly into Tehran’s embrace and risk further regional instability by stoking sectarian strife.