Ms Richardson expressed relief that security guards at the museum were safe and unharmed.
“It could have been very, very dangerous.
“We always take security and safety very seriously – we have very strong protocols in place,” she said, adding the museum robbery was part of an unwelcome trend “around the world”.
“These are very siginificant items for the stories of Wales,” said Ms Richardson said of the stolen Bronze gold.
“Any value would be meaningless because you can’t recreate that level of history. You can’t put a price on it. They cannot be replaced they are so special
“But ultimately – these items – we want people to share them, to see them, to learn from them, and to do that you have to put them on display.
“Even with the top-notch specially designed cases we have at St Fagans, nothing can ever be totally secure.”
The museum remains open the public and will be hosting a museums conference over the next two days, although the main building, the café and the indoor galleries are currently closed.