A series of tornadoes has killed at least 45 people in the southern United States. The states of North Carolina, Virginia, Alabama and Arkansas were worst hit with homes ripped from their foundations and cars overturned.

In North Carolina alone 21 died as more than 60 tornadoes struck two of its counties.

The extreme weather began on Thursday in Oklahoma, where two people died, before moving across the south coast states on Friday and hitting North Carolina and Virginia on Saturday. Authorities said seven people died in Arkansas; seven in Alabama; seven in Virginia; and one in Mississippi.

More than 240 reported tornadoes were created from the storm system, including 62 in North Carolina, but the National Weather Service’s final numbers could be lower because some tornadoes may have been reported more than once.

Saturday was North Carolina’s worst day for tornadoes since 1984, when 22 twisters killed 42 people and injured hundreds more.

Scott Sharp, a local meteorologist, said such conditions were extremely rare in North Carolina.

“The atmosphere was unstable, which allows air to rise and fall quickly, creating winds of hurricane strength. There was also plenty of moisture, which acts as fuel for the violent storms, and winds at different heights were moving in different directions, creating the spin that makes tornadoes.”