KILIS, Turkey – More than 1,300 Syrians fled to Turkey overnight to escape growing violence in their country as rebels try to expand their hold inside Syria's largest city despite two weeks of withering counterattacks by President Bashar Al-Assad's troops.In Pretoria, South Africa, Secretary of State Hillary Clinton said the defections of Syria's prime minister and other senior officials increase the urgency of planning for the ouster of Syrian President Bashar Al-Assad. Clinton was in the South African capital Tuesday when she told reporters that it is important to make sure that Syrian state institutions remain intact once Assad loses his grip on power. Clinton spoke a day after the defection of Prime Minister Riad Hijab, the latest in a string of high-level departures from the Assad regime. Clinton said she would raise these issues when she travels to Turkey for talks on Syria Saturday. Aleppo-based activists said clashes were going Tuesday near the historic city center in Bab Jnein and Sabee Bahrat districts, suggesting the fighters were making inroads. They said intense bombardment of the town of Tal Rafaat near the Turkish border sent scores of people spilling into Turkey for safety. A Turkish government official said 1,328 Syrian refugees had crossed the border by midmorning — nearly double the number of refugees who reached Turkey on Monday. The official spoke on condition of anonymity in line with government rules. The new arrivals would increase the number of Syrians who have found refuge in Turkey, which has served as a staging ground for rebels fighting Assad's regime, to close to 48,000. “We are expecting a massacre in Aleppo. The regime is bringing reinforcements to the city because they consider that if Aleppo falls, the regime will fall,” said a Syrian refugee in Turkey who identified himself as Abu Ahmad. “The city is being bombed from the air and ground,” he said, adding he was in daily contact with residents still in the city. The rebels appeared also to be bringing in reinforcements. A video posted online by activists Tuesday showed a large group of Free Syrian Army rebels in military fatigues and carrying shoulder carried rocket propelled grenades and automatic rifles, announcing they were joining the “Unification Brigade,” the main group of rebel fighters in Aleppo, to assist in the “liberation” of the city. Meanwhile, a Syrian rebel group which has claimed responsibility for the kidnapping of 48 Iranians in Damascus said three of its hostages were killed in shelling by government troops Monday. – Agencies