A transformer exploded in midtown Manhattan on Wednesday, creating a huge plume of smoke and sending pedestrians fleeing from the scene, but police said the blast did not look suspicious.
"It doesn't look suspicious at this time," a police spokesman told Reuters.
A witness reported that a building had collapsed, but New York City police said the building had not fallen, but was "shaky."
"There is debris falling, get back," a fireman told onlookers. People were being kept a block away.
"There was a thundering noise like a hundred freight trains going by and a plume of what looks like steam as high as 10 stories," said former Reuters correspondent Irwin Arieff.
The explosion took place near 42nd Street on the east side of midtown Manhattan during the evening rush hour.
Subway trains were diverted away from Grand Central station.