A sharpshooter killed a top ISIS executioner and three other jihadists with a single bullet from nearly a mile away -- just seconds before the fiend was set to burn 12 hostages alive with a flamethrower, according to a new report.

The British Special Air Service marksman turned one of the most hated terrorists in Syria into a fireball by using a Barett .50-caliber rifle to strike a fuel tank affixed to the jihadi’s back, the UK’s Daily Star reported Sunday.

The pack exploded, killing the sadistic terrorist and three of his flunkies, who were supposed to film the execution, last month, the paper said.

The ISIS butcher -- who reportedly delighted in burning hostages alive -- had been on a US “kill list” for several months, sources told the paper, which did not identify the sniper or the executioner.

Click to read the story in the New York Post.