At least 1,100 people have been evacuated from Homs, a city that has been under siege for nearly three years during Syria's civil war. But twice as many are still left in the city, either too sick or scared to leave. And a UN official says those evacuated are often just "a bag of bones.
The Syrian war has changed in its three years. The Free Syrian Army forces that were attacking the Assad regime and its government soldiers are now locked in battle with Islamic fighters, who were once their allies. PBS Frontline journalist Muhammad Ali slipped across the Syrian border to report on this "second front" in Syria.