The ceasefire is due to expire at 2101 GMT on Monday.
It comes as world powers push for a wider cessation of hostilities between rebels and regime forces and a resumption of UN-brokered peace talks.
The Britain-based Syrian Observatory for Human Rights said a woman and a child were among the three civilians killed when the rebels rained rockets down on several districts of western Aleppo city.
Fighting in Aleppo flared up late last month, and more than 300 people have been killed in the violence.
Syria's five-year war has killed more than 270,000 people and displaced millions.
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It comes as world powers push for a wider cessation of hostilities between rebels and regime forces and a resumption of UN-brokered peace talks.
The Britain-based Syrian Observatory for Human Rights said a woman and a child were among the three civilians killed when the rebels rained rockets down on several districts of western Aleppo city.
Fighting in Aleppo flared up late last month, and more than 300 people have been killed in the violence.
Syria's five-year war has killed more than 270,000 people and displaced millions.
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