https://www.iana.org/dnssec/ceremonies
CloudFlare has published an account:
There are multiple redundant sites and backups of the keys, so an attack aimed at destroying a site should not alone be a problem. Even if all all sites and backups were destroyed, there is a window where a new key can be constructed (approximately between 3-6 months worth of operational zone-singing keys are prepared in advance for the root zone).
Despite the folklore around these ceremonies that there are 7 people with "the keys to the Internet", those seven only retain a metal key that is used to access a safety deposit box in the ICANN/IANA facility, each of which contains a smart card of which there is an "m-of-n" configuration to activate HSMs containing the actual key.
Again, I am misunderstanding the information here, but the keys are actually useless, even if you get your hands on all of them to attempt an incursion against the building where the KSK is, you would not be able to do anything because the security of that place is probably good enough to counter an attack like that, and supposing the attack takes place the other DNS servers would simply disconnect from the root and serve the information that they have until it gets outdated. So the only scenario that I can picture in my head is one where a terrorist attack goes against the building to disrupt the functionality of the whole system for anarchy reasons.