The marksman took out the crazed Islamist killers just as they were about to slay 12 hostages in a chillingly cruel manner.
The jihadists were preparing to use a flamethrower to kill the group when the heroic British sniper made his shot-of-a-lifetime.
From a distance of 1,500 metres, the SAS soldier shot at the flamethrower’s fuel tank, causing a massive explosion which took out the executioner and three other sick jihadis who were filming.
The sniper, part of an ultra-skilled team of marksmen targeting ISIS members on a secretive ‘kill list’, had been tipped off about the wanted executioner’s location in northern Syria.
A source told the Daily Star online: “The SAS team moved into an overwatch position above a village where they were told the execution was going to take place.
“Up to 12 civilians were going to be murdered – eight men and four women. They were suspected of being spies.
“None of them were agents. The ISIS killers knew that but just wanted to instil fear into the local population.
“The executioner gave some sort of rambling speech over a loud hailer then when he finished the SAS sniper opened fire.
“The bullet struck the fuel container and it exploded immediately. He was incinerated and several of his henchmen were also killed.”
This is not the first time an SAS sniper has shown incredible skill and composure under pressure.
In December, another marksman killed five ISIS fighters en route to carry out a suicide attack – using just three bullets.
The unnamed veteran, who joined the SAS a decade ago, saved potentially hundreds of lives by unleashing three well-aimed shots from a distance of 800m.
The sniper shot the first jihadi in the chest, detonating his explosive device and killing him instantly, along with two ISIS guards sat in a nearby car.
The second terrorist was killed with a headshot, as he and the third man tried desperately to get back into the locked factory.
The third jihadi also died when his explosive vest was set off by a third and final well-aimed shot from the colour sergeant.