Here's a first hand report from a good friend who was right there.

I was on 42nd and Lex, about to walk into the subway when the steampipe popped.

First there was a huge >>kaboom<<, followed by what I now know to be
escaping steam, but to my neophyte ears sounded like a jet engine
roaring.

The crowd of pedestrians stampeded... many into the subways, dragging
me along with them (the entrance at Lex on the corner of 42nd).

The plume of steam jetted hundreds of feet in the air, and small
chunks of asphalt rained down intermittently.

My friend and I fell back to 43 and lex, smoked a few cigs (in light
of the asbestos being tossed around, was idiotic... at best) and
watched women take off their heeled shoes and run "bat outta
hell"-like down the street.

All the while many were going on about the terrorists. I kind of
sussed out that it was a HVAC type dealie when the torrent of smoke
contined to flood the street.

Lots of people went to bars immediately following the blast.. which is
a fairly common response to abject horror. ^_^

In the end, everyone seemed pretty calm immediately following the
event. I'm amazed that noone got cooked outright by the steamblast, or
walloped by the debris.

This guy is a pretty cool person, I'm glad he was OK.