 After forming over the Arafura Sea, the storm moved southwards and affected the city with Category 4 winds on the Australian cyclone intensity scale, while there is evidence to suggest that it had reached Category 3 on the Saffir-Simpson Hurricane Scale when it made landfall.Tracy killed 71 people, caused 837 million in damage (1974 dollars) and destroyed more than 70 percent of Darwin's buildings, including 80 percent of houses.Tracy left more than 41,000 out of the 47,000 inhabitants of the city homeless prior to landfall and required the evacuation of over 30,000 people.