Massive blackout hits California, Arizona and Mexico

Five million people were without power on Thursday, with many likely to remain out of service for another day or two.

There was traffic chaos. San Diego was the worst affected city, where all outbound flights were cancelled.

An investigation is looking into why the blackout spread from Arizona, where a piece of equipment was switched off. Extreme heat may be a factor.

'Like an oven'

Officials say that a power line between Arizona and California was knocked out of service after an employee carried out a procedure at a substation in Arizona.

"There appears to be two failures here - one is human failure and the other is a system failure. Both of those will be addressed," said Damon Gross, a spokesman for APS.

Daniel Froetscher, a vice-president at APS, told the Associated Press news agency it was "not a deliberate act".

"The employee was just switching out a piece of equipment that was problematic," Mr Froetscher said.

In Los Angeles, trains were stopped because there was no power for lights and signalling, and a number of people had to be rescued from stuck elevators and theme park rides.

California's two nuclear reactors were forced to shut down; Kazinform cites BBC.

To learn more go to www.bbc.co.uk