The group said Syrian warplanes bombed the town after the death of the solders.
Mohammed Kanaan, an activist based in Maaret al-Numan, said rebels stormed army positions south of the town and killed many soldiers.
‘‘The town is witnessing some of the worst clashes in weeks,’’ said Kanaan via Skype.
Maaret al-Numan is on the highway that links Damascus with Aleppo, Syria’s largest city and commercial center that has been the scene of clashes between rebels and troops since July.
Abdul-Rahman said the rebels captured another major post on the highway linking Salamiyeh and Raqqa in what could be a major move to disrupt another route of supplies for the regime. It said nine troops were killed in Monday’s fighting.
An amateur video showed more than 15 men inside a room who identified themselves as troops who were posted on the highway in the Syrian desert near the town of Bukraya.
Activists also reported violence in other areas, including the eastern province of Deir el-Zour, central region of Homs as well as villages and towns near Damascus International Airport south of the capital.
A resident in Damascus, speaking on condition of anonymity for fear of government reprisal, told The AP that he was hearing cracks of gunfire and explosions inside and outside the capital early Monday.
The Observatory said troops clashed with rebels in the Damascus neighborhoods of Salhiyeh and Rukneddine north of the city in which three people were killed. It said the clashes were ‘‘the most intense in the neighborhoods since the revolution began.’’
Associated Press writer Bradley Klapper in Washington contributed to this report.