Russia backed Assad's troops have shelled neighborhoods of Damascus after overnight clashes with freedom fighters, who launched deadly attacks on the criminal Alawite military elsewhere in the country on Saturday.
The bombardment of the southern neighborhood of Tadamon in the capital early on Saturday followed street fighting with freedom fighters there.
Alawite troops also shelled the nearby neighborhood of Hajar Aswad.
Alawite regime forces have been able to recapture most areas of the capital liberated by freedom fighters in a July offensive, though freedom fighters continue to stage attacks using hit-and-run tactics in areas where they enjoy popular support, and recently shot down a Russian helicopter.
Meanwhile, gun battles between Alawite troops and liberation forces are being fought in the country's biggest city, Aleppo.
Freedom fighters captured the main Assad's air defense building in Al Bukamal on the Iraqi border. They seized ground-to-air missiles that could boost their ability to down Alawite aircraft.
The assault late on Friday came after a liberation attack on the Abu Zohur air base in Idlib province in the northwest, where the Free Syrian Army downed a Russian MiG warplane shortly after takeoff earlier this week.
In their assault in Al Bukamal, freedom fighters also captured 16 Assad's air defence personnel and attacked the nearby Hamdan air base.
The seizure of the defense headquarters was a major coup for the freedom fighters. In retaliatory shelling in the town of some 60,000 people, the Alawites killed at least five civilians.
They were among a total of 125 people killed in nationwide on Friday - 74 civilians, 29 Alawite soldiers and 22 freedom fighters.
The freedom fighters also destroyed a dozen aircraft on the ground in their attacks on air bases in recent days as they countered the Alawites' use of Russian MiG warplanes and helicopter gunships against them.