This is awful. And so strange. 3 people all drown in a pool? A river? A lake? An ocean? A swimming pool? shrugs
Hard to say, but multiple "rescue attempt" drownings occur. There was one in the UK where four people including a policewoman drowned in an attempt that started with one person jumping off a seawall to save a dog.
In a pool though, wonder how that happened. Will be curious to see if there is any follow up coverage.