COPENHAGEN, Denmark — Thieves carrying out a daring daytime robbery smashed a security case at a cathedral in Sweden and stole gold and jewel-encrusted crowns from the early 1600s before hopping on bicycles and escaping via a nearby lake, police said.

The two men pulled off the heist at Strangnas Cathedral at noon Tuesday and vanished aboard a speedboat or jet skis into the vast patchwork of lakes around the city, located 60 kilometers (37 miles) west of the Swedish capital of Stockholm, police said.

The stolen artifacts included a gold crown and an orb dating to 1611 that were made for King Karl IX’s funeral, as well as a jewel-encrusted crown dating to 1625 that was used in Queen Kristina’s funeral. The items were on display at an exhibition, and visitors were inside the cathedral when they were taken.

“The alarm went off when the burglars smashed the security glass and stole the artifacts,” Catharina Frojd, a spokeswoman for the 14th century cathedral, told The Associated Press.

Strangnas Cathedral said on its website that the stolen pieces were kept “in accordance with the prevailing safety regulations in locked and alarmed displays.” It gave no further details.

Police sent out a helicopter and boat to hunt for the thieves but found nothing. Authorities said no one was hurt in the robbery but didn’t provide further details.