When a group of horses gets loose there is no telling why they do what they do. We once had all of our yearlings get out and wander about 5 miles down the road. It was terrifying because we realized they were out before we ever got a call about where they could be so we were basically tracking them down the road. We found and caught them all, but it was scary.
Oh man, how scary. That's pretty much been my worst nightmare since I got my yearling. The old man doesn't have it in him to go too far these days but I have nightmares about trying to catch the baby. He almost got away from me on a trail walk one day and all I could think about was how the hell would I track him down on foot on hundreds of miles of wooded trails with numerous road outlets. We don't go anywhere without a curb chain now.
The other week someone here hit and killed three horses (one instantly, two had to be put down by sheriff's dept) at around 5 in the morning, on a crappy snowing day. The driver was in a coma but is doing okay now. Very scary, and my nightmare too.