Sheriff’s deputies in Ohio have found 11 children locked in cages less than 3 1/2 feet high inside a home, but a couple have denied they had abused or neglected the children.

America’s worst blackout should have been contained by operators at Ohio’s FirstEnergy firm, a three-month US and Canadian investigation has concluded.

The Ohio power company under the spotlight following the biggest blackout in America’s history has said there were problems, including strange voltage fluctuations, in the Midwest power grid hours before its transmission lines failed.