The Observatory said seven people, including three children, were killed Wednesday by government shelling of villages in the area.
Rami Abdul-Rahman, who heads the Observatory, said the fighting around the town of Arnabeh intensified Thursday, a day after rebels captured it. He added that the rebels captured two nearby army posts.
In Lebanon, security officials said 150 people, mostly women and children, walked for six hours in rugged mountains covered with snow to reach safety in the Lebanese border town of Chebaa. They said eight wounded Syrians were brought on mules from Beit Jan and taken in ambulances to hospitals in Chebaa.
The officials, who spoke on condition of anonymity because they were not authorized to speak to the media, said the Syrians fled from the town of Beit Jan, near the Golan Heights.
The Yarmouk Martyrs Brigade, a rebel group active in southern Syria, said in a statement on its Facebook page that its fighters stormed an army post between the villages of Sahm al-Golan and Shajara.
Activists on Facebook pages affiliated with rebels in Quneitra announced the start of the operation to "break the siege on Quneitra and Damascus' western suburbs."
The fighting moved closer to Israel as President Barack Obama was visiting the Jewish state for the first time since taking office more than four years ago.
Associated Press writer Albert Aji in Damascus contributed to this report.
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