As others have stated, it only takes a second! I was a CBR with my then 5 yo daughter. I bent over to put my beach bag down next to a poolside chair, stood up, and my daughter was GONE! I looked in the pool (thank God she knew how to swim!) No daughter. I checked the slide. No daughter. I looked all around the poolside. No daughter. That's when I got worried and told the lifeguard. Security was notified, and the area was "locked down." I gave a discription, and my daughter was found playing in the sand, next to the pond, on the other side of hedge, not 10 feet away from the lounge chair! I just couldn't see her from my position. The same thing can happen in a crowd. I've had my child by the hand, but have been jostled by others hard enough to break my grasp. I was able to spot him instantly, and grab him, but it did involve pushing others out of the way.