A line of violent thunderstorms roared across middle America, killing six people in two states, with several tornadoes touching down in Oklahoma and high winds pounding rural Kansas.

A deadly winter storm that caked America’s centre with a thick layer of ice claimed at least 17 lives and blacked out more than 600,000 homes and businesses.

Animal-rights activism is colliding head-on with rural tradition in Oklahoma, where voters will decide on November 5 whether to ban cockfighting in one of the last three US states to allow it.