NICOSIA (AFP) - Syrian forces killed at least 15 civilians on Sunday, six of them in the flashpoint region of Homs that has been under siege for several weeks in an operation to crush dissent, a rights group said. Security forces killed one person during a raid in the Bayyada district of Homs city, and another civilian was shot dead from the roof of a building in the town of Qusayr, said the Syrian Observatory for Human Rights. Four civilians were also killed in Al-Khalidiyeh when troops and security forces raided the neighbourhood in Homs city, said the Britain-based watchdog. "Several people were wounded, some seriously, and the death toll could rise," it added. Near Damascus, six people were killed, including a 14-year-old boy, and 13 civilians were wounded as troops fired "indiscriminately" and made arrests in a raid on Rankuss district, said the Observatory. Security forces killed at least two people and wounded eight others when they shot at mourners during the funeral of a man who had died in the eastern oil hub city of Deir Ezzor, it said. Another person was killed in the Kafarnubol area of Idlib province in the northwest after being arrested by security forces "for selling fuel to militants," the group added. Clashes also erupted between regular troops and deserters in the region of Talbisseh, another town in Homs province, said the watchdog in statements received in Nicosia. "Two troop transporters were destroyed." In the southern province of Daraa, cradle of eight months of dissent against Assad's autocratic regime, mutinous soldiers attacked a military bus, wounding several troops, it said. Syrian authorities said security forces killed 12 gunmen during clashes with "terrorist groups" in Homs, state-run news agency SANA said, adding that similar clashes had occurred in Idlib and Daraa. The Observatory's chief also reported that regime forces were carried out acts of vandalism in the Kafarnabuda region of Hama, further north of Homs province. "Troops and security forces plundered shops, torched homes and cars owned by activists and arrested several militants," in Sunday morning raids, said Rami Abdel Rahman. The Local Coordination Committees which organise anti-regime protest said several rallies were staged across the country, including four small ones in Damascus where demonstrators urged foreign intervention.