Millions endure record cold without power in US

More than 500 people sought comfort at one shelter in Houston. Mayor Sylvester Turner said other warming centers had to be shut down because they lost power.

Utilities from Minnesota to Texas implemented rolling blackouts to ease the burden on power grids straining to meet the extreme demand for heat and electricity.

Blackouts of more than an hour began around dawn Tuesday for Oklahoma City and more than a dozen other communities, stopping electric-powered space heaters, furnaces and lights just as temperatures hovered around minus 8 degrees.

Oklahoma Gas & Electric rescinded plans for further blackouts but urged users to set thermostats at 68 degrees Fahrenheit (20 degrees Celsius), avoid using major electric appliances and turn off lights or appliances they are not using.

Nebraska's blackouts came amid some of the coldest weather on record: In Omaha, the temperature bottomed out at 23 degrees below zero overnight (minus 30 Celsius), the coldest in 25 years.