Retired firefighter Marty Logan said he spotted the tornado when it knocked down power lines, causing flashes of light, and saw a radio tower's blinking lights go black shortly after midnight. He later saw a man emerge from a twisted, wrecked sport utility vehicle that had been tossed along the side of the road.

  "The guy had blood coming down his face," Logan said, adding that he saw people walking down the street covered in blood when he went to a hard-hit neighborhood. "It was scary, because I knew it was after midnight and a lot of people were in bed."

  Search teams were scouring rubble for trapped and injured as the sun came up.

  "They're still going door to door and in some cases, there are piles of rubble and they are having to sift through the rubble," said Michelann Ooten, an Oklahoma emergency management official.

  The National Weather Service said the storm systems were weakening and that additional tornadoes were unlikely. But forecasters warned that strong thunderstorms were expected as far east as Michigan.