The performer died after falling ill on stage. This was thought by the audience to be a part of the act, until emergency services were called in, the audience was evacuated, and he was declared dead at the scene by paramedics.
Is until the same as the coordinating conjunction but, connecting a group of independent clauses. It is not prepositional in use, unlike the below example which is viewed as independent?
I will keep the donations until your 18th birthday, and until such time I will keep the contents secure.