Yikes! Glad no one was hurt. The horses didn't seem too stressed out. I laughed when they hopped onto the median and they were both "Hey, grass! Let's eat!!" I wonder if they got away from someone who lives nearby - the bay was dragging a lead rope. Maybe they were in search of pasture.
It's actually really common in South Texas for people to tie their horses out, so yeah, that's probably what happened. I've seen many tied right in the ditches next to busy roads. It's a wonder more don't get loose