More than 200,000 people have evacuated Syria's largest city, Aleppo, as fighting there intensifies between rebel forces and President Bashar Assad's regime.
Rebels currently control much of Aleppo. But the United Nations says the Syrian government is fighting back with mortars, tanks and helicopter raids.
As Syrians flee the fighting, neighboring countries like Jordan have already seen an influx of refugees.
"We believe that more are expecting and trying to cross, probably tonight," Kamel Deriche, UNHCR Deputy representative in Jordan, said.
Turkish officials ordered troops to its border in light of possible refugees. They also put in place more armored combat vehicles and missile launchers.
Meanwhile, Syria's top diplomat in London said he could no longer represent the regime and defected Monday.
Britain's Foreign Office said that Khaled al-Ayoubi, the charge d'affaires, told officials that he wasn't willing to represent the regime any longer. It's the latest high-profile defection of a diplomat from Syria over the bloody crackdown since March 2011.