One person is already killed after hurricane Michael slammed into the US state. It's believed to be the most destructive storm to hit Florida's Panhandle in a century. And a third strongest hurricane to ever strike the US mainland. Local authorities say nearly half a million residents are without power. Michael hit Florida as a category four hurricane. And has since been downgraded to a category one as it moves inland into Southwest Georgia. Authorities warned there’s a risk of dangerous flash floods and tornadoes in a storm's path.