Before I post this, I must tell you that this is NOT a timeline unless it has to be. So here goes.
On September 11, 2001 a strange occurance happened in both towers. While a janitor was sweeping a floor, he hit the fire alarm causes that tower to evacutate. Right after they were all done evactuating, planes hit the towers. Lukily, most of the people were out of it when it did happen. Tell me, how could this unlikely accident change history and save millions?