The person who died went into cardiac arrest.
A large number of people went into complete panic, IMHO largely because they've been whipped up into a state of utter fear by terror scares, psychic predictions of apocalyptic carnage by key governmental officials, etc.
Meanwhile, in reality, these pipes rupture CONSTANTLY downtown, because they are ancient, and the wisest way of dealing with this sort of occurrence is to GO HOME and not gawk, and most importantly, shower immediately and either wash or trash your clothes, because they used asbestos to insulate those pipes in the old days.
Samples were taken before sundown, and there should be more conclusive information available by 10 PM, for those who trust the judgements that will be made. They are still checking the tunnels one by one under the station, so the trains will be backed up WAY late. A lot of tenants in the area have been barred from their apartments for the time being (fortunately, a lot of those folks are out of town for the summer).
Traffic is bad all the way down to Union Square and I would say up to about the mid fifties by Sixth Avenue.
There is a creepy sulfur smell all about. I don't recall that smell at any prior steam explosions, but it's not an entirely unfamiliar smell either, so, who knows?