Explicación de lo sucedido via reddit:
"You guys aren't seeing the video how it actually happened. Everyone assumes the person laying in the middle of the street is one of the bikers.
What really happened:
The female race official (khaki pants, white polo shirt, and white cap at the start of the video) was waving the racers to the far side of the road. One of the racers on a bicycle struck her, causing her to fly into the lane where the race vehicle (not a random car in the race course, as everyone is assuming) was driving.
The car didn't even hit her - and it slammed on the brakes fast enough to avoid the bicyclist who originally hit the female (if you look closely when the car stops, there's obviously a bike laying on the street in front of it).
So basically, a bicyclist slammed into the lady, causing her to go into the other lane where the car was (and yes, the car WAS supposed to be there). The car didn't hit anyone, just a bicycle vs race official.
Then the dude coming from the other way didn't have enough time to slow down out of the turn (plus being in the middle of the pack, it's highly unlikely he saw the pack being waved over until it was too late), thus running into/jumping her.
Also, the title of this post is correct - the course should NOT be laid out where the bikes come back down the same road as they went. That's a huge problem if someone is lagging behind the rest of the racers when the first group gets turned around and back to that spot... crash waiting to happen.
TL;DR: bike hits chick, car slams on brakes and avoids everyone, 2nd bike hits chick, chick goes to hospital."
