The Local Coordination Committees (LCC) in Syria confirmed the incident in Talbiseh and said people had started to flee to safe zones.
Syria has been gripped by almost constant fighting since the regime launched a violent crackdown in response to anti-government protests in March 2011, triggering a conflict, which has spiraled into a civil war.
The UN has stopped updating its death toll for the country because an official count had become too difficult to verify.
More than 100,000 people have been killed during the three-year conflict, which has left more than 6.5 million people internally displaced according to the UN.
Nearly 2.5 million Syrians are also registered as refugees in neighboring countries, including Turkey, Lebanon and Iraq.