A cascading power outage that swept across the eastern U.S. and Canada Thursday afternoon caused massive confusion and disruption at East Coast media companies.

In New York, millions of office workers poured into streets and onto bridges. Movie theaters went dark; film and publishing companies were evacuated; Broadway houses canceled evening performances.

The lowly radio was suddenly the preeminent form of information as cell phones, computers, TVs and virtually all other power-fed appliances were rendered useless.

Radio stations were forced to broadcast over phone lines as the blackout sent most residents and tourists on a mad dash for batteries and candles.

Meanwhile, production continued on large-scale film and TV projects. “The Sopranos,” “The Stepford Wives” and “New York Minute” shoots — all lensing in Gotham on Thursday — relied on generators for power.

But even as officials expressed optimism that Manhattan would have the lights back on by 10 p.m., several showbiz sectors were bracing for revenue losses that could amount to tens of millions of dollars:

  • TV networks interrupted regularly scheduled broadcasts to air wall-to-wall news coverage of the blackout.

  • Broadway shows, sporting events and concerts were duly canceled.

  • Movie theaters in affected areas were expected to remain shuttered Thursday night.

  • Newspapers struggled to put out smaller editions of Friday papers.

State officials initially attributed the outage to an overload of the Niagara-Mohawk power grid, which generates power for stretches of New York and Canada. Officials said the outage was a natural occurrence and not related to terrorism.

But in New York, where memories of 9/11 are still raw, a familiar anxiety gripped office workers as they crowded around radios and sought to gauge the magnitude of the crisis.

New Yorkers’ fears were intensified by the collapse of phone communication and widespread paralysis of city services. Flights were grounded at area airports, public transportation came to a stop and civilians found themselves directing traffic at intersections.

Shortly after 6 p.m., New York Mayor Michael Bloomberg sought to quell those anxieties, announcing that power was expected to return by 10 p.m. Gradually, electricity was restored to outlying areas of New York and New Jersey. New York City’s subways resumed limited service around 8 p.m.

Box office shortfall

But studio execs in Hollywood girded themselves for a box office shortfall on Thursday night.

“We’re resigned to the fact that this is a natural disaster,” said Universal Pictures distribution chief Nikki Rocco. The studio had “American Wedding” booked into more than 3,000 theaters Thursday.

“We’re going to lose a big chunk of business,” Rocco said.

Distribs also were concerned about prints shipping to Eastern theaters for today’s openings, though MGM distribution topper Eric Loomis said prints for “Uptown Girl” had already reached their venues.

AMC spokesman Rick King said houses in New York, Cleveland and Toronto closed for the day after the blackout hit. Even if the power were restored, he said, it would be hard to reassemble theater staff.

But a Friday blackout would have been far more injurious for studios and exhibs.

“The economic impact won’t be severe for a Thursday,” King said. “And the good thing is that it looks like we’ll be able to get open (today) for the new pictures.”

TV news scramble

TV news outlets quickly mobilized, piecing together coverage anchored at national news desks, interspersed with video from New York and phone interviews.

‘We went down rather dramatically,” ABC News spokesman Jeffrey Schneider in New York said. “Hundreds of TV sets and lights went out. But seconds later, the backup generators came on.”

Ted Koppel anchored a special broadcast of ABC’s “World News Tonight” from Washington. Brian Williams opened the “NBC Nightly News” by noting, “It is only thanks to emergency generators and a whole lot of scrambling here that we are able to say this Thursday night, Good evening from NBC News headquarters in midtown Manhattan, where we are in the midst of what appears to be a colossal and history-making blackout.”

Broadway.com stopped selling tickets for evening performances as 22 shows went dark. The lucky show was “Say Goodnight, Gracie,” which does not have a Thursday night perf. Other area theaters, including the Goodspeed Opera House and Norma Terris Theater in Connecticut, announced performances would proceed as scheduled.

MTV closed its studios, including a VH1 taping of band the Thorns. A Bob Dylan concert at Hammerstein Ballroom was postponed a day. The Mets-Giants game at Shea Stadium was canceled.

The taping of “Late Night With Conan O’Brien” was canceled, though the entertainer taped a special blackout-themed opening segment.

Gray Lady down?

At the New York Times in Times Square, the newsroom was operating on emergency power, with phones working and 25% of the computers functioning.

The Times was planning to publish a Friday edition, said spokeswoman Catherine Mathis. She said the paper’s main printing facility in College Point, Queens, did not have power. But the Times plant in Edison, N.J., had not been affected.

The Times transmits from its 43rd Street headquarters to plants throughout the country, and officials were still trying to figure out if that process was still possible.

After 9/11, there were plans to create a newsroom at the Edison plant. Those plans have not yet been put into effect.

In Cleveland, the Plain Dealer lost all power, and 15 reporters and editors were sent 25 miles south to the Akron Beacon-Journal. President and publisher Alex Machaskee planned to use the Beacon-Journal’s press to publish a 24-page paper with only eight pages of news.

(Meredith Amdur, Carl DiOrio, Josef Adalian, Gabriel Snyder and the Associated Press contributed to this report.)