A separate strike on nearby Sabqa killed two women and a young girl, it said.
The raids are part of a six-month offensive by government forces that has chipped away at rebel-held villages and farmland across Eastern Ghouta, according to the Observatory.
Douma, the largest town in the Eastern Ghouta area with more than 100,000 residents, is surrounded and regularly shelled by regime forces.
Syria's five-year conflict has left more than 300,000 people dead.
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The raids are part of a six-month offensive by government forces that has chipped away at rebel-held villages and farmland across Eastern Ghouta, according to the Observatory.
Douma, the largest town in the Eastern Ghouta area with more than 100,000 residents, is surrounded and regularly shelled by regime forces.
Syria's five-year conflict has left more than 300,000 people dead.
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