Two Syrian men were being taken to hospital late yesterday when dozens of Druze in the town of Majdal Shams stoned their ambulance, forcing it to stop and dragging the wounded men from the vehicle.
The mob then beat one of the men, who was later pronounced dead, and seriously wounded the other. An Israeli soldier and another officer with the ambulance were also lightly wounded.
Israel has a policy of providing humanitarian assistance to wounded Syrians who seek help by crossing over to the Jewish state and has vowed to maintain the practice.
Syrian Druze are traditional allies of President Bashar al-Assad, and the rioters yesterday likely believed the men in the ambulance were rebels.
Yaalon labelled yesterday's violence a "lynching" and vowed action.
"We won't be able to ignore it, and law enforcement authorities will deal with it heavy-handedly," he said in a statement.
Officials say there are 110,000 Druze in northern Israel and another 20,000 in the Israeli-occupied Golan. Members of the minority are followers of a secretive offshoot of Shiite Islam.
Tensions have flared in Druze areas of northern Israel and the Israeli-occupied Golan Heights after rebels surrounded a government-held Druze village on the Syrian side last week.
Syria's official news agency SANA stated the two men being transported yesterday were "terrorists from Al-Nusra Front."
Syrian authorities label all those fighting to oust Assad "terrorists" and make no distinction between jihadist groups like Al-Nusra and other internationally-backed forces.
Israel denied the wounded men were rebel fighters and called them civilians.
Damascus has regularly accused Israel of backing forces fighting the regime.