No injuries were reported, but acrid smoke still filled the air an hour-and-a-half later, and Fire Chief Mike Meyers said 300 people evacuated four nearby office buildings.
"I saw the manhole cover shoot up in the air and the fire shoot up out of the ground," said Shiryelle Reese, who was walking back to her office from lunch when the manhole erupted in flames around 1:40 p.m. "The fire, it was like a volcano type of thing."
Rachel Peters watched from the fifth floor of her office building.
"The ground kind of shook," she said. "I heard a boom. Then we ran down the stairway."
Con Edison spokesman Allan Drury said that smoking underground cables caused the fire. Utility crews were at the scene, but no power outages were reported. Officials closed 40th Street between Seventh and Eighth avenues.
A fire official said that after the blast, firefighters checked carbon monoxide levels in the basement of a nearby building.
Though not nearly as serious, the fire recalled the rupture of a steam pipe beneath a street on the other side of Manhattan in 2007.
Dozens of people were injured and a woman died of a heart attack.
