Syrians cross the border from the town of Ras al-Ain to the Turkish border town of Ceylanpinar, December 4, 2012.

Damaged buildings along a street in the al-Khalidiya neighborhood of Homs, December 5, 2012.

Syrians walk past damaged homes during heavy fighting between Free Syrian Army fighters and government forces in Aleppo, Syria, December 4, 2012.

Free Syrian Army fighters with weapons stand guard at the frontline against forces loyal to Syrian President Bashar al-Assad in the Al-khalidiya neighborhood of Homs, December 4, 2012.

Buildings in Aleppo, Syria, December 4, 2012.

Buildings damaged after a Syrian Air Force fighter jet fired missiles at Houla, near Homs, December 3, 2012.

Free Syrian Army fighters are seen at Houla, near Homs, December 3, 2012.

Residents flee their homes after shelling by forces loyal to Syria's President Bashar al-Assad in Houla, near Homs, December 3, 2012.

This citizen journalism image provided by Lens Young Homsi, which has been authenticated based on its contents and other AP reporting, shows anti-Syrian regime mourners carrying victims of shelling in Homs, Syria, December 3, 2012.

Residents walk past buildings damaged in heavy fighting between Free Syrian Army fighters and government forces in Aleppo, Syria, December 2, 2012.