At least five people have been killed and multiple injuries reported after a string of up to seven deadly tornadoes tore through US Alabama, toppling trees, demolishing homes, and knocking out power to thousands.

Iran PressAmerica: "The confirmed deaths were in Calhoun County, in the eastern part of the state, where one of the multiple twisters sprang from a 'supercell' of storms that later moved into Georgia," said John De Block, a meteorologist with the National Weather Service in Birmingham.

"Search and rescue efforts were complicated by strong weather that continued to hit the region. Radar debris signatures showed a tornado that formed in southwest Alabama traveled roughly 100 miles (161 km) and stayed on the ground for about an hour and 20 minutes," De Block said.

He said on-sight investigations would determine the strength of the storms, but based on the debris signatures, "we’re pretty confident we will find at least seven tornadoes passed through the state on Thursday."

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