Somewhere on the site, I actually gave an illustration of the exact damage that occurred, which buildings were damaged from Arasaka towers collapse, but I am too lazy to dig it up right now, I may repost it if I can find the images on my HD.
I found the thread:
http://forums.cdprojektred.com/threads/27325-The-canon-conclusion-to-the-4rth-Corporate-War
But I am just gonna repost the relevant bits here...
Here is Night City as presented in the full color map that came with the Sourcebook. The red highlighted portion is the area where the damage was limited.
At the end of the book Firestorm: Shockwave, it definitely describes the nuke as being underground, in the foundation of the building. The nuke itself doesn't seem to do any damage to the surrounding city, but the collapse of the towers causes the larger twin towers of Araska to fall. 1 to fall northeast, the other to fall West and slightly north, over onto other buildings, causing massive damage to WNS, The Stock exchange, Marshals department store, a night club(presumably Rainbow Nights), the 10th street center, the West Plaza Executive Tower, and some abandoned Militech Facilities are all completely destroyed, Other buildings take massive damage from debris as the two smaller Arasaka towers collapse to the eats and south west... including the US Federal Building, The Japanese Consulate, and the Microtech and WNS Towers. The Damage caused by both nuke, and complex collapse, is detailed fully on page 133 of Firestorm Shockwave.
This map is a close up of the damage zone that shows the buildings destroyed or damaged by the event.
The Nuke caused the 4 Arasaka Towers to topple in an x formation outward. The large NW tower was the first to fall, then its twin, then the two smaller towers...
This map shows the path of destruction caused by the Buildings, RED is for the two larger towers, who pretty much obliterated what they fell over on, except for the FED and Consulate, which only sustained massive damage, as opposed to outright destruction... Yellow is for the two smaller towers who managed massive damage, but did not destroy the buildings they impacted with.
During this fight, Johnny and Rache are confirmed dead. Thompson is grievously wounded, perhaps dead... Morgan and Adam Smasher are on the rooftop when the building collapses, and are presumed Dead. Saburo Arasaka has fled to Japan.
In the epilogue, Kei Arasaka, Saburo's heir, is forced to download his consciousness via Soulkiller into a digital prison by Rogue, Spider Murphy, and Shaitan.
Now... the important bits...
First, the nuke was detonated underground, it was a small low-yield device, primarily designed for excavation. As such, upon closer inspection, the damage from the nuke to the city is almost inconsequential. It was certainly NOT detonated at the top of the tower, if it was, all the iconic characters would be dead, as it is clearly stated to have been detonated while some were still on it, and others were hovering above.
Second, while the damage caused by the collapsing towers was heavy, it was not the major city destroying book described by V3, there is no way the body count reaches even a million.... It happened in the middle of the night, the body count would be less than that of 9-11.