New York ? A fire at a utility plant Saturday blacked out power for tens of thousands of people in a swath of lower Manhattan and snarled transportation around the city.

Crews had restored electricity by early evening, largely ending an emergency that brought back disconcerting memories of the days after Sept. 11.

National Guardsmen wear protective masks as they prepare to investigate a transformer fire at a Consolidated Edison plant in lower Manhattan. The fire Saturday caused outages throughout the area, including Greenwich Village, Tribeca and Soho.

During Saturday’s outage, residents around the fallen World Trade Center again found themselves navigating dark hallways and descending gloomy stairwells for dozens of floors as sirens wailed outside.

National Guardsmen, a fixture on the streets after the terrorist attack, returned, helping police direct traffic on roads crowded with onlookers. A stretch of a major highway along the east side of Manhattan,was closed.

Most subway traffic through downtown was suspended or rerouted. Smoke could be seen for miles.

There was no evidence, though, that the midafternoon fire was caused by anything other than an accident, Mayor Michael Bloomberg said.

The apparent cause was a transformer explosion at the plant, which provides power for much of lower Manhattan, said Joe Petta, a Consolidated Edison spokesman.

“It sounded like a jet plane crashing and then a big thing of black smoke went up in the air,” witness Michael Koster said.

“First we heard a big noise then we saw the black smoke,” deli owner Alex Darwish said.

About 63,000 customers lost power in areas south of 14th Street to the lower tip of Manhattan, the utility said. The neighborhoods affected included Greenwich Village, SoHo and Tribeca.

Nurses were seen working with flashlights at St. Vincent’s Hospital, but administrators said critical care was not affected.

“Having gone through previous disasters such as 9-11, we are a pretty well-oiled machine,” said hospital vice president William Grice.

Consolidated Edison said some of its workers were inside the plant at the time of the explosion.

No injuries were reported.