A pair of thieves made off with “significant” gold artefacts in a targeted attack that saw them in and out of St Fagans National Museum of History in just four minutes, fleeing as a police helicopter swooped in overhead.

“We believe they entirely knew what they were after, they were so focused,” said Jane Richardson, chief executive of National Museum Wales.

CCTV footage captured the thieves smashing their way into the building on the edge of Cardiff. South Wales Police were called at 00:30 BST, arriving within five minutes.

“It feels like someone has stolen from the family of Wales,” said Ms Richardson. No details have been shared on the “irreplaceable” stolen items.

Ms Richardson said CCTV footage of the robbery was “emotional to watch”.

“They knew exactly where they were going,” she told BBC Radio Wales Breakfast.

“They didn’t look left or right,” she said.

“It looks like they’ve been scoping out in advance and that they’d come for specific items.

The authorities have not specified which items were taken, or their value.

The museum’s Bronze age collection includes gold ingots, bracelets, and a lunula necklace .

“These items they took are very special and they didn’t bother trying to take anything else,” said Ms Richardson.

“My colleague called the police and they were there within five minutes with a helicopter.

“Unfortunately, they were so organised that they got away before the police were able to apprehend them.”

Det Insp Chambers urged members of the public to come forward with any information, stressing “no matter how small, [it] may be relevant to the investigation”.

Founded in 1948, St Fagans is one of Wales’ most popular heritage attractions – and is one of seven national museums under the curation of Amgueddfa Cymru.

The museum, in a leafy area on the outskirts of the city, was redeveloped in 2018 with three new galleries. Celtic roundhouses and a prince’s court are among the ancient buildings found in this green and quiet corner of the capital.

“It’s been very upsetting for us all. We’re absolutely devastated,” said Mr Richardson.

“These items don’t belong to us at the museum, they belong to the people of Wales. The Amgueddfa is a family which everyone in Wales belongs to and it feels like the family of Wales has been attacked.

“People love the items, they’ve cared for them and it felt like a bereavement yesterday.”

Ms Richardson said there was relief security guards in place at the museum were safe and unharmed.

“It could have been very, very dangerous.

“We always take secururity 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”.

“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.”