That actually happened to me and I almost killed my baby brother because of it. We were 3 and 7 at the time. I saw my brother fall in a pond in a neighbours yard, I dove in after him forgetting I couldn't swim. The neighbour saw me drowning and safed me, but he didn't know my brother was in there too. I swallowed water so couldn't speak coherently for a few seconds but eventually managed to say my brother was in there, he dove immediately and saved him as well. That was more than 30 years ago and I remember it like it was yesterday.