From CNN:
At least 20 homes in Atlanta’s historic Cabbagetown neighborhood were flattened by a tornado that ripped through downtown Atlanta on Friday night, a spokeswoman for the mayor said.
Firefighters fear there could be people dead inside the ruins of a collapsed loft complex in the same neighborhood, the spokeswoman said.
There have been no deaths confirmed from the tornado, but at least 15 people were treated at two hospitals. Most of the injuries were minor cuts, scrapes and bruises, officials said.
The Fulton Cotton Mill Lofts, just east of downtown Atlanta, collapsed in a “pancake fashion,” Atlanta Fire Chief Kelvin Cochran said early Saturday.
The tornado that ripped through the heart of the city damaged the roof of the Georgia Dome during a college basketball game, shattered windows and ripped roofs from buildings before continuing into several residential neighborhoods.
The building that houses CNN was at the epicenter of the storm — sitting next to the dome and hotels where thousands of basketball fans attending the Southeastern Conference tournament were at least temporarily displaced.
Photo from Flickr user photognome:

From our friend Currer Bell, who was at work downtown at the time:
Just as I was settling into my overnight shift at work last night, a tornado ripped through downtown Atlanta right in front of my building. The windows up here on the 24th floor were bowing from the suction on the outside. It was a pretty scary there for about five minutes. Naturally, my curiosity lead me downstairs and out into the street. Chunks of buildings, insulation, power lines and tons of shattered glass were lying in the road. The ground crunched underneath my feet as I made my way across the glass-strewn street toward the CNN Center, which is one block from my office. Big pieces of metal siding hung precariously out of trees, the ones that made it through the wind. Other not-so-lucky trees lay on top of parked cars and in the road.