A video that shows a Syrian government fighter jet bursting into flames while under fire from rebels was posted on the Internet on Monday. The downing of a warplane would be a rare event for lightly armed rebels faced with the superior weaponry of President Bashar Assad's forces. Related articles: Book: Barak opposed strike on Syrian reactor Syria: Israel, US, Gulf allies backing rebels Rebels: Assad using 'mass-killing weapons' in Aleppo In recent months the government has begun to use its air power to try to crush a 17-month-old uprising. The video uploaded on YouTube was filmed by an opposition activist who said he was in the north-eastern town of Mohassen in Syria's Deir al-Zor province. It was not clear when it was filmed and it was not possible to verify the location. The footage shows a warplane streaking through the skies amid heavy gunfire. The jet suddenly erupts into flames and begins to swirl, leaving a trail of smoke. "God is greatest! A MiG fighter jet has been hit in the town of Mohassen," the activist shouted. There was no indication from the video that the jet had been hit by rebel gunfire or an anti-aircraft missile. 'Plane was flying too low' An opposition source working with rebels in the area told Reuters the rebels used anti-aircraft guns to down the jet. "It was a Mig-21 brought down by a 14.5 anti-aircraft gun, the biggest in the rebel arsenal. The plane was flying too low and was within range. We have no information whether the pilot survived," the source said. Rebels, whose armory is made up mostly of assault rifles, explosives and rocket-propelled grenades, say they are unable to compete with the army's air power. In recent weeks, fighter jets have been seen firing rockets on rebel-held villages and the northern city of Aleppo. Follow Ynetnews on Facebook and Twitter Receive Ynetnews updates directly to your desktop