Sao Paulo - A blackout spreading across nine states of southern and central Brazil was caused by a failure at a hydroelectric dam, the country's energy minister said. The power outage Tuesday night affected 40 million people and left about 800 cities - including Sao Paulo, Rio de Janeiro, Belo Horizonte and Brasilia - in the dark.
Energy Minister Edison Lobao speculated that a storm had disconnected power transmission lines at the Itaipu dam, which provides more than 20 per cent of Brazil's energy.
Technicians were working to get the power supply back on line quickly, both Lobao and Itaipu's operating company said.
The power outage began shortly after 10 pm (midnight GMT) and was starting to be restored early Wednesday.
In the meantime, thousands of people were trapped in elevators, subways and suburban trains. Road traffic was also chaotic as the power outage darkened traffic lights, and the police were put on high alert as an outbreak of crime was feared.
Only large office buildings and hotels with generators were lit, correspondents for the German Press Agency
