Police in Sweden are searching for robbers who stole two crowns worn by King Charles IX and his wife Queen Christina from Strängnäs Cathedral.

The two thieves launched their operation at around lunchtime on Tuesday, and two men were seen jumping into a motorboat that sat moored in the lake adjacent to the church before making their escape. Police searched for them by both water and air with no result.

The 1611 gold burial crowns belonging to King Karl IX and his wife Queen Christina were originally interred with the couple but were later exhumed and had been on display in a locked cabinet in the Strangnas Cathedral, located 100 kilometers (60 miles) west of Stockholm.

“We have as yet no value of the stolen goods, except that it is a national treasure,” Dangardt told AFP.

“Several people were seen leaving the church by boat or waterscooter after the theft. We have spoken to witnesses, but we are interested in further information from anyone that has made any observations,” he said.

The theft occurred just before noon on Tuesday, and police quickly had helicopters, patrols, and search dogs looking for the perpetrators but their efforts have so far proved fruitless, Dangardt said.

“There is of course going to be a lot of media interest in these types of objects. There will be pictures in the media. It’s just not possible to sell these kinds of objects,” the national police coordinator for thefts of cultural artifacts, Maria Ellior, told news agency TT.

“So we can only speculate about (the thieves) intentions,” she added.