The casualties late yesterday were the first since Russia said three days ago that an agreement was reached with the Syrian opposition on the boundaries for a de-escalation zone for the eastern suburbs of Damascus.
The Syrian Civil Defense group, more popularly known as the White Helmets, and the Britain-based Syrian Observatory for Human Rights say the airstrike on Arbeen killed eight and wounded several others.
They said today that the dead included children and women.
The chief of the Russian general staff, Col. Gen. Sergei Rudskoi, said earlier that Moscow deployed military police to monitor the cease-fire in a safe zone in the eastern suburbs of Damascus.