Atlanta remains in a state of emergency after a tornado struck late Friday night, leaving rubble all over the city and thousands of people without power.

The twister came through the city at speeds of up to 200 kmh, and tore through 10 km of the dowtown core.

Emergency crews sifting through damaged homes found the bodies of two people in separate locations in the region.

There were more storms Saturday throughout Georgia, killing one person in Polk County and another in Floyd County, both near the Alabama line. Storms in South Carolina and Alabama left thousands without electricity.

In addition to the two fatalities, Friday night's storm left 27 injured.

The streets around downtown Atlanta landmarks such as the Georgia Dome, Phillips Area, the CNN Center and Centennial Olympic Park were also littered with glass and other types of rubble. Power lines were downed, affecting about 19,000 customers.

Judy Pal, a spokeswoman for the Atlanta police, said that about 350 emergency personnel were trying to clear the streets of debris before the second storm hits the city.

"We could have some problems with buildings that are already under stress," Pal said, noting that one building has already collapsed.

Pal said the cost of the storm will be "enormous."

• In Pictures:  Destruction in Atlanta

On Friday, a tornado warning was issued for downtown Atlanta just eight minutes before the storm hit, but there was no warning for spectators inside the Georgia Dome watching play in the Southeastern Conference basketball tournament.

"Ironically, the guy behind me got a phone call saying there was a tornado warning," fan Lisa Lynn said. "And in two seconds, we heard the noise and things started to shake. It was creepy."

The Fiberglas fabric roof started to ripple, catwalks swayed and insulation fell upon the court during overtime in the Mississippi State-Alabama game.

Fans headed to the exits, and teams to the locker rooms.

"I thought it was a tornado or a terrorist attack," said Mississippi State guard Ben Hansbrough, whose team won 69-67.

The game was delayed by an hour, and the roof was left with at least two visible rips. A later game was postponed.

Play between the NBA's Atlanta Hawks and Los Angeles Clippers at a different facility about 800 metres away wasn't really disrupted.

Downtown events for Saturday in Atlanta were cancelled, including the St. Patrick's Day parade.

If the Atlanta event is confirmed as a tornado, it will be the first to hit a U.S. city's downtown since Aug. 12, 2004 in Jacksonville, Fla. Atlanta itself hasn't had a tornado strike inside the city since 1975.

"The storms that produce tornados don't really care if there's a city there or not," Kourounis said. "Nature is very unpredictable."

With files from The Associated Press