Observatory director Rami Abdulrahman said 235 people had died in Atreb and surrounding areas.
More than 4,400 people have been reported killed in the earthquake in the northwest, according to a UN agency, most of the deaths in Syria.
Government and rebel forces also clashed in another part of the northwest near the government town of Saraqeb, the Observatory said, while government forces shelled the outskirts of two villages in Hama province.
The reports could not be independently verified.
The World Health Organization has said it was particularly concerned about the welfare of people in the northwest, where many have felt abandoned as supplies run out in other parts of the vast disaster zone.