Are there instances in which an entire sentence constitutes a focus--new information? Consider the following scenario:
Three people are talking together about a mutual friend who is in the hospital for a hernia operation.
A fourth person enters the room abruptly and interrupts the conversation with any one of the following announcements:
a) "The President has just been shot."
b) "The school has just been quarantined." c) "There's a can of paint leaking all over the kitchen floor."
On one hand, each sentence can be broken into topic & comment. Topics are "The President," "The school" and "A can of paint" respectively.
On the other hand, all of the information is new to the three listeners. None of it pertains to the original topic of discussion.
Is there any sentence in which sentences a) through c) could be called foci from beginning to end because all of the information in them is new?