How 'Game of Thrones' set a world record for the most people on fire in the 'Loot Train' scene

Last year "Game of Thrones" set a world record during their season seven "Loot Train" scene. But Daenerys Targaryen and Drogon can't take all the credit. Stunt coordinator Rowley Irlam and his team set 20 stunt people on fire for a single shot. And 73 stunt performers were set on fire throughout the scene. But how do stunt people actually get set on fire? Doesn't it hurt? Business Insider talked with stunt coordinator Rowley Irlam to find out what it takes to safely set someone on fire.