Evacuate? Hah! Standard modus operandi against anomalous plagues will most likely involve lockdowns and kill-on-sight orders! This is SCP-008 we're talking about! It's an anomalously incurable (since the Foundation only contained it, they probably never found a cure despite their advanced tech) prion with perfect 100% lethality rate, and it turns people into zombies!
If it's the Foundation, the place gets a lockdown, everyone gets captured and segregated between infected and non-infected, those who caught 008 will be herded off and terminated, the healthy ones get amnestics treatment and will forget the incident, disinformation ops were launched and will make everyone think a terrorist attack happened via bioweapons, end of story. Life goes on, just another day with the Foundation.
If the GOC responds, on the other hand, everyone dies. Whole place gets nuked. Disinformation ops start, everyone thinks a terrorist attacked the place with nukes, end of story. Life goes on, and GOC gets their ego inflated some more and will gloat over the Foundation's "incompetence" and how their way of outright eliminating threats works better than capture and containment.