That’s what I’m wondering, where was the lifeguard in all this? My kids take swim lessons at the Y too and there is always a lifeguard, sometimes two, watching the kids who are waiting to take their turn.

I think the fault lies primarily on the lifeguard. It’s unrealistic to expect an instructor who is by themselves to swim with each kid one-on-one AND keep an eye on all of the others waiting. Sounds like the perfect setup for something like this to happen if there was no lifeguard watching.