Complex sentence: The other man (who later died of his injuries) had poured petrol over himself and was on fire as he ran into the airport terminal, writhed on the floor and was then held down by a brave member of the public.
Split into simpler sentences: The other man (who later died of his injuries) had poured petrol over himself and was on fire as he ran into the airport terminal. This man then writhed on the floor and was held down by a brave member of the public.