A man passes heavily damaged vehicles while surveying storm damage on the campus of Union University in Jackson, Tennessee Feb. 6, 2008. (Xinhua/Reuters Photo) Photo Gallery>>>

    WASHINGTON, Feb. 6 (Xinhua) -- Dozens of people were killed and hundreds more injured as more than 50 tornadoes slammed into a string of the southern U.S. states late Tuesday and early Wednesday, U.S. media reported.

    Authorities went door-to-door early Wednesday in search for more victims after the devastating tornadoes ripped through the southern U.S. states of Tennessee, Arkansas, Kentucky and Mississippi, the reports said.

    CNN said at least 45 people were killed. The Associated Press put the toll at at least 44, including 24 people in Tennessee, 13 in Arkansas, and seven in Kentucky.

    Latest CNN video pictures showed the impact of the tornadoes --roofs of houses ripped off and big trees uprooted in Arkansas, turning the severe weather into a widespread disaster.

    "This was an extraordinary night," the Associated Press quoted Arkansas Governor Mike Beebe as saying. "When it's compounded by darkness, that makes it that much more difficult."

    The earliest reports came at midnight Tuesday, saying that a severe storm collapsed part of the roof and walls of a shopping mall in Memphis, Tennessee, but no casualties were reported.

    In Atkinds, central Arkansas, a couple and their 11-year-old daughter were killed after their home was directly hit as a tornado touched down in the residential area where they lived.

    Local police said debris including parts of houses, left by the devastating tornados, blocked U.S. Highway 62.

    At least six tornadoes touched down between Oxford, Mississippi, and Jackson, Tennessee, and more than 30 people were injured in the two states, the Associated Press said.

    At least 13 people in Memphis were taken to hospital with two people in a critical condition.

    The Union University in Jackson, 120 kilometers northeast of Memphis, also suffered some damage in the fierce winds. Eight students were trapped in a battered dormitory at the university and were later rescued.

    Before dawn Wednesday, the severe weather system moved on to Alabama and brought heavy rains and gusty winds to the southern U.S. state, causing several injuries.

    The brutal weather came at the end of the Super Tuesday primaries in several states. As the extent of the damages quickly became clear, candidates including Hillary Clinton, Barack Obama and Mike Huckabee paused in their victory speeches to honor the victims.

    On Aug. 29, 2005, Hurricane Katrina, one of the worst natural disasters in U.S. history, devastated the Gulf Coast, killing at least 1,212 people, displacing thousands and costing the country up to 200 billion U.S. dollars.