How Did Harvey Dent Transform Into Two-Face

The Joker captured Harvey Dent and his girlfriend, Rachel Dawes. He placed them in warehouses rigged with explosives. The Joker told Batman the wrong address. So when Batman got to the warehouse, he thought he was saving Rachel, but it actually was Harvey Dent who was saved by Batman. There were canisters of gasoline all over the place. Harvey Dent's face was soaked in gasoline. When the explosion occurred, Harvey Dent suffered neurological damage. The left side of his face was badly burned. Rachel was killed when the other warehouse exploded. From then on, Harvey Dent was called Two-Face.