I don't think there is enough information to say. Back when I went to college, there was a minor scandle involving a groundskeeper that was accused of animal cruelty. I happened to actually witness the event, and what happened is that a squirrel was trying to cross the road, misjudged, and was hit by a car, ending up flung onto the grassy bank near the road, where it lay twitching. A crowd of students gathered, and there was lots of handwringing, and "Oh, someone should do something." One woman ran to get a groundskeeper who was working near by. He took one look and went to get his shovel, decapitated the squirrel to kill it, and put it in the bags the groundskeepers are provided with to dispose of dead animals they may find. I was amazed at how quickly the rumors diverged from the truth, even that some students had come across the groundskeeper secretly torturing the squirrel and that he had killed it to destroy the evidence of his torture.
We don't know what species these birds were, how old the fledglings may have been, or anything else. With many birds, if the nest is disturbed in any way, the parents will abandon the fledglings to starvation, and many birds are not amenable to being raised in captivity. Being drowned would be far more humane.