At least 47 people have been killed across several cities in western Syria during the last two days of fighting between pro- and anti-government forces, an opposition group said Thursday.

Most of the deaths have occurred in the city of Rastan, where at least 27 people were killed amid heavy shelling, according to the Local Coordination Committees of Syria — a network of opposition activists who organize and document anti-government demonstrations.

Twelve others were killed in the western city of Homs, the group reported.

The Syrian army has been fighting units that had defected from the military, said the LCC and the Syrian Observatory for Human Rights, a London-based opposition group.

The Syrian government, meanwhile, says it is engaged in a campaign against terrorists.

CNN is unable to independently confirm death tolls or events in Syria, which has restricted access to many parts of the country by international journalists.

Thursday’s report coincides with a mob attack of government supporters in Damascus that U.S. ambassador Robert Ford narrowly avoided, a U.S. government official said.

Ford, who has been outspoken against the Syrian government’s use of violence against protesters, is seen by pro-government supporters as an activist more than a diplomat.

At the time of the attack, Ford was visiting Hassan Abdul Azim, head of the opposition Arab Socialist Democratic Union.

According to Azim, about 50-100 people gathered at the door to his office and began to chant loudly when Ford arrived. Some of them even tried to break down the door, he said.

The crowd protested rowdily for more than two hours, he said.

Azim could not confirm what Ford was attacked with, but he said that tomatoes that had apparently been thrown were cleaned up off the street afterward.