It was taken by Associated Press photographer Evan Vucci (bio here), and is a potential Pulitzer Prize winner. The Atlantic calls it “A legendary American photo.”
The article gushes, “However you feel about the man at its center, it is undeniably one of the great compositions in U.S. photographic history.”
Its author adds, “Although I am deeply relieved that Trump survived this assassination attempt, I am no fan of his,” which is exactly my sentiment as well. (Note, he article is behind a paywall, and unless you’re a subscriber, you can only read a few paragraphs.)