Philly.com: Center City shaken:
A fire in an underground electric cable yesterday spewed smoke, ignited gases that blew manhole covers into the air, and forced the evacuation of about 5,000 workers from two office towers near City Hall.
The ripple effect of the lunchtime drama snarled traffic in Center City and threatened to disrupt the evening rush hour.
But the fire was put out by 3, and power was quickly restored to most of the buildings in the area bounded by 15th and 16th Streets and Market and Chestnut Streets.
Livia was in the area and posted some shots on Flickr.