The US national weather service has issued an ‘extreme red flag’ warning for wildfires in Los Angeles county, Ventura county and the Simi valley. ‘I don't know if I've ever seen us use this warning,’ forecaster Marc Chenard said. ‘It's pretty bad.’ Dangerous fire weather conditions cover over 34,000 square miles, and 21 million people have been warned they may need to leave ‘at a moment's notice’ as the 70 mph winds threaten to bring more devastation to areas already ravaged. Power cuts have left 1.5 million people without electricity.