Alawy said the government has been shelling gatherings of people in recent days, since the Free Syrian Army liberated the town from Syrian government forces.

British diplomat Alistair Burt said Monday he was "appalled" by what, if verified, "would be the most recent in a long line of human rights violations and abuses committed by the Syrian regime." Italy's foreign ministry issued its own statement saying "these horrific images offend human sensibilities and our concept of civilization."

Many Syrians face shortages of food and other necessities as winter sets in. The United Nations estimates that more than 2.5 million people need humanitarian assistance.

To address this crisis, Turkish Deputy Prime Minister and government spokesman Bulent Arinc said the Turkish Council of Ministers would donate 37,000 tons of flour to Syria, effective immediately, the semi-official Turkish news agency Anadolu Agency reported.

Meanwhile, dissidents in the city of Homs said six rebel fighters died Sunday night after inhaling a white gas that had no smell, according to Rami Abdulrahman, director of the opposition Syrian Observatory for Human Rights.

"Gas was released and spread in the area after members of the regime forces threw canister bombs," Abdulrahman said Monday. "... The activists said that everyone who (inhaled) the gas felt severe headaches and some had seizures."

The observatory called for the International Committee of the Red Cross to investigate the case.

CNN cannot independently confirm government or opposition reports from Syria, as the government has restricted access by journalists.