Updated

Even though lights went out Thursday throughout much of the Northeast, wireless networks and Internet connections allowed companies with backup strategies and people with battery-charged cell phones and laptops to keep communicating.

Several large telecommunications providers, including the company that supports the vast majority of Internet traffic worldwide, said they immediately switched to backup generators on the East Coast and could continue doing so for several days.

"We lost all utility power out there, but we immediately went to battery power for a few seconds, at which point all of our major generators kicked in," said Margie Backaus, chief business officer of Foster City, Calif.-based Equinix, which operates Internet Business Exchange centers that serve more than 90 percent of the world's Internet routes.

Equinix runs three data centers in New Jersey, each of which lost power, but they "operated normally, and it was totally seamless to customers," Backaus said. "They've had no disruptions whatsoever."

All operations at Level3 Communications, which runs one of the most expansive Internet backbones in the world, were running Thursday after switching to diesel generators.

It could continue using diesel until Saturday and after that, it could switch to battery backup power for at least 45 more hours, said Level3 spokesman Paul Lonnegren. "I don't see any big disaster with the Internet going down," Lonnegren said.

Dave Johnson, spokesman for the network services division of AT&T, said it also switched to backup generators to keep traffic flowing on the East Coast. It did not have any disruptions with Web hosting or Internet services in the first 90 minutes after the blackout began at about 4 p.m. EST.

"My fingers are firmly crossed that it stays that way," Johnson said.

Although communications continued, it was not conversation as usual.

AT&T had to digest a big spike in long-distance traffic, which slowed some connections or required users to make multiple calls before getting through.

The carrier normally handles about two million calls every five minutes. But as word of the power outage spread, the figure jumped to 2.6 million calls every five minutes.

Wireless coverage in New York City was unreliable as a result of excessive use of the network, but many calls went through after multiple attempts.

Verizon Wireless spokeswoman Brenda Raney said the company was experiencing "heavier than usual" call volume, making it impossible to connect every call the first time. But she said that all of Verizon's cell phone towers had backup power, and none was entirely disabled.

New York Mayor Michael Bloomberg blamed the blackouts on an overload on the Niagara Mohawk Power Grid, which supplies power to at least five states. He assured panicked New Yorkers that blackouts were not the result of a terrorist act.

Computer experts at the CERT Coordination Center received numerous inquiries Thursday whether power outages were related to the computer worm known as W32/Blaster, which disrupted millions of personal computers in the past week, or other hacker activity.

But computer security experts said the worm did not appear to be the source of the blackout.

"There's nothing we're seeing to indicate these are related in any remote way," said a spokesman for Cupertino, Calif.-based Symantec.