Syrian rebels say they shot down a Syrian air force jet and blamed an al-Qaeda-linked group for killing the pilot.
Two leading groups, Jaysh al-Islam and Ahrar al-Sham, which formed a pact last year, both say the plane was shot down.
Syrian state media said the crash was caused by a technical fault.
Jaysh al-Islam, the larger of the two groups, posted footage online which it claimed showed the pilot being held after ejecting from the jet.