My understanding is that with reports written by AP, the first sentence is a carefully wordcrafted summary of the whole story. AP is particularly sticky about that when it comes to Fair Use. AP might or might not win a lawsuit over quoting a first sentence, but I won't push TBR's luck. If I notice a story is from AP, I usually avoid quoting the first paragraph.
That's an interesting tip. It can be hard figuring out how to parse an excerpt from AP, because their stories are often three paragraphs from start to finish. At least they' actually "paragraphs," as opposed to those incomprehensible strings of a dozen one-sentence chunks separated by carriage-returns. I prefer the classical-styled paragraphs that have at least five sentences: Introduction, Point 1, Point 2, Point 3, Conclusion.
College English Composition 101.