Washington: The United States and parts of Canada suffered the worst electricity blackout in history, affecting 50 million people for several hours.

The cities without power included New York, New Jersey, Cleveland, Michigan and Detroit in the US and Ottawa and Toronto in Canada.

President Bush came on TV to congratulate the people for the way they faced the disaster and assured them of all Federal help to their state and local governments.

He said that when the immediate problems have been solved, it will be time to investigate why the failure occurred. His own view, he said, is that the US power grid will have to be modernised.

Bush assured the country that the massive blackout was the result of a system failure, not any terrorist act.

However, authorities are taking no chances. Air patrols are being intensified and, on the streets of New York, police are at maximum strength. Firemen have also been mobilised.

Without electricity, trains stopped in their tracks between stations at tunnels. Several hundred thousand people were guided to the next station and safely pulled out onto the platform. With no trains and no buses on several streets, many commuters walked miles to reach home.

Huge power outages also threw air travel in the two countries into chaos, blacking out major airports and stranding masses of flights.

Stuck for hours were people caught between floors in elevators on top floors of skyscrapers.

An Indian American told ABC-TV that he was lucky that the elevator stopped between the first and second floors. Even then, he had to wait until the top could be removed and a ladder brought to enable him to get out.

PTI