Night was falling on the East Coast and engineers had still not sorted out the exact cause of the cascading outage that knocked out power in New York City, Toronto and points west in a matter of minutes.
"It clearly shows that the grid system did not work as well as it should," New York Gov. George Pataki told a news conference as hundreds of thousands of New Yorkers hiked across the city's bridges to the bright lights of New Jersey.
It did not appear that the problem was a lack of electricity despite the sultry August weather, and Pataki insisted that New York's statewide grid had both the power and the transmission capacity to meet demand.
After grid operators ruled out terrorist sabotage and a computer virus, it became likely that the outages were the result of some sort of mechanical or operational failure that wound up disabling the grid's transmission lines and forcing 21 power plants -- nine of them nuclear -- off line in an estimated three minutes.
"Major transmission lines were out of service at the time of the disruption," the North American Electric Reliability Council informed the news media without being able to offer much more in the way of details.
Exactly what triggered the cascading shutdown was unclear Thursday night.
"Cascade" is another word for a domino effect in which overloaded power lines automatically go off line to avoid major physical damage to the lines themselves. The theory Thursday evening was that when the first plant went off line, other plants automatically increased their production to cover the lost electricity from the first plant.
With more power pouring onto the grid, the transmission lines were in danger of overloading. As a result, the transmission fail-safe system began shutting down in order to keep electricity off the lines.
"There has been no physical damage to any part of New England's transmission system or any generators," maintained Stephen Whitley, chief operating officer of ISO New England, which runs the New England grid. "Our system held up well. The part of our system that went down is the part of the system that is closest to New York and is the weakest part of our system."
In addition, the loss of power can sometimes cause power plants to go off line since they too need electricity to run and require a careful and methodical procedure to restart.
"The problem is when these power plants went off line, they get cold," Michael Gent of the North American Electric Reliability Council told CNN. "The ones that use natural gas can be back in an hour or so, the ones that burn coal might take four to eight hours, the nuclear plants might take half a day."
The Nuclear Regulatory Commission said late Thursday that nine nuclear plants in New York, Michigan, New Jersey and Ohio, with a huge total capacity of nearly 8,000 megawatts, automatically shut down as a result of the line closures and would be off line until the transmission lines were humming once again.
"This is a very complex and technical issue to bring these plants back up, but we're up to the task," Gent added.
Experts were debating cause into the late evening hours. Another debate that will likely take place in the coming days will be the nation's move toward a national power grid that will be even more closely intertwined than the current system.
The idea is to streamline the movement of power from one area of the country to another during times of shortages.
Thursday's outage may cause some lawmakers and industry officials to reflect upon what seems to be a double-edged sword in which trouble in one location causes problems for utilities and their customers hundreds of miles down the line.
President Bush on Thursday night called for modernization of the power grid, calling the outage "an interesting lesson for our country."
"We will find out why (this happened) and we will deal with it," Bush said.
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