Swans Fledging

My grand-daughter has been able to watch a pair of swans lay and hatch 5 cygnets recently. They are on a pond locally to her and the nest was very close to a wildlife viewing platform. Six days ago the cygnets started to hatch and all 5 were out within a day or two. Today they have gone back and the nest has been broken up and there is no sign of either parents or the cygnets.

I thought that was a little early for the cygnets to take to the water and a little disturbed that something may have happened to the family.

Any ideas?