That same thing happened at camp during one of our trail riding club
outings. A Careflight helicopter taking off from the nearby site of a
rider accident blew over a shade cover and spooked a horse tied to an
unhitched trailer with the same results.
That was one ride I didn't go to and I'm thankful for that. The rider
had very serious injuries in a separate accident, and did survive,
though never wants to ride again. The horse had minor injuries.