True. You also have to be very careful when you try to aid a drowning person who is still struggling. It’s dangerous because their adrenaline-driven fear can cause them to pull you under in the process and I wouldn’t doubt that’s exactly what happened here. It’s best to grab something to reach out to where they are and pull them into shallow water.
I was trained to swim under them, pull them under water and grab them there, under the arms and around the neck so they can not grab you. Return to the surface and swim them back to safety. We had to do this in a matter of seconds.