In this Sunday, April 15, 2012 photo, Syrians walk between destroyed buildings in the Inshaat neighborhood of Homs, Syria. (AP Photo)

In this image made from amateur video released by the Shaam News Network and accessed Sunday, April 15, 2012, smoke rises from buildings across the city following purported shelling in Homs, Syria. (AP Photo/Shaam News Network via AP video)

This image made from amateur video and released by Bambuser Saturday, April 14, 2012 purports to show smoke from shelling in Homs, Syria. (AP Photo/Bambuser via AP video)

In this picture taken on Sunday March 25, 2012, a Syrian rebel stands guard in front of a damaged building, at Khaldiyeh neighborhoods in Homs province, central Syria. (AP Photo)

In this citizen journalism image taken on Saturday, March 24, 2012 and provided by Edlib News Network ENN, a Syrian boy stands next to damaged cars which were attacked from Syrian government forces shelling at Sarmeen town in Idlib province, northern Syria. (AP Photo/Edlib News Network ENN)

In this picture taken on Tuesday, March 20, 2012, shops and homes are seen after they were destroyed by Syrian government shelling in Rastan town in Homs province, central Syria. (AP Photo)

In this picture taken on Tuesday March 20, 2012, a damaged part of a Syrian army tank that attacked by the Syrian rebels is seen next to a destroyed house , at Rastan town in Homs province, central Syria. (AP Photo)

In this picture taken on Tuesday March 20, 2012, a damaged house that was destroyed by the shelling of the Syrian government forces, at Rastan town in Homs province, central Syria. (AP Photo)

In this picture taken on Tuesday March 20, 2012, a destroyed Syrian army tank which was attacked during clashes between the Syrian government forces and the Syrian rebels, in Rastan area in Homs province, central Syria. (AP Photo)

In this Tuesday, Feb. 21, 2012 citizen journalism image provided by the Local Coordination Committees in Syria and accessed on Wednesday, Feb. 22, 2012, houses are seen damaged by Syrian government forces shelling in Homs, Syria. (AP Photo/Local Coordination Committees in Syria)

In this Monday, Feb. 20, 2012 citizen journalism image provided by the Local Coordination Committees in Syria and accessed on Tuesday, Feb. 21, 2012, houses are seen destroyed from Syrian government forces shelling, at Baba Amr neighborhood in Homs province, Syria. (AP Photo/Local Coordination Committees in Syria)

In this Monday, Feb. 20, 2012 citizen journalism image provided by the Local Coordination Committees in Syria and accessed on Tuesday, Feb. 21, 2012, a damaged home is seen from Syrian government forces shelling, at Baba Amr neighborhood in Homs province, Syria. (AP Photo/Local Coordination Committees in Syria)

This image grab of footage uploaded on YouTube on March 20, 2012 allegedly shows a burning vehicle and gas cylinders, mainly used for cooking, strewn across a street after a mortar shell struck a gas depot store in the central restive Syrian city of Homs. ( -/AFP/Getty Images)

Houses, destroyed by shelling by regime forces, are seen in the central town of Rastan, near Homs, on March 13, 2012. (STR (FILES)/AFP/Getty Images)

A picture shows damaged buildings in the city of Rastan, near the flashpoint city of Homs, on March 9, 2012. ( -/AFP/Getty Images)

A view of a deserted street strewn with debris in the restive city of Homs, some 160kms north of the Syrian capital Damascus on February 25, 2012. (-/AFP/Getty Images)