Arwel Jones, Director of Public Services at the National Library of Wales, told ITV News "our concern now is for the collection", and that it will take time for the extent of any damage to be estimated.
More top news
A dry and clear start to the night ahead of cloud and showers which will push in by the early hours!
Missed tonight's Wales at Six? Catch up here.
William and Sophie Richards have won £1 million on a lucky dip after Mr Williams made an impromptu trip to pick up some mushy peas.