Priceless 18th-century jewels were stolen from a German museum.

Thieves broke into Dresden’s Grünes Gewölbe, one of the largest treasure collections in Europe, and spirited away 18th-century artifacts worth hundreds of millions of dollars. The director of Dresden’s Staatliche Kunstsammlungen, or state art collections, said the stolen items include three “priceless” sets of diamonds, according to the The Guardian.

The robbery took place early Monday morning, after fire broke out at a nearby electrical distribution point and deactivated the museum’s alarm system. A surveillance camera still managed to catch two men breaking into the museum, and police responded shortly before 5 a.m. By that time, the suspects had escaped. A possible connection between the fire and the museum heist is under investigation, according to local news media.

The Grünes Gewölbe, or Green Vault, was created by Augustus the Strong, Elector of Saxony, in 1723, making it one of the oldest museums in Europe. The historic section of the museum, which is where the robbery took place, contains over 3,000 Baroque masterpieces, including jewels and gold, crystal, and diamond objects. According to The Guardian, German media described the theft as the biggest since World War II.

According to the New York Times, Michael Kretschmer, leader of Saxony, wrote on Twitter:

Not only have the Staatliche Kunstsammlungen been robbed, but also we Saxons! The history of Saxony cannot be understood without the Grünes Gewölbe. The treasures found here have been acquired by the people of our state for years.

At least one object from the museum was saved. The “Dresden Green diamond,” weighing in at 41 carats, is current on loan to the Metropolitan Museum of Art for its exhibition “Making Marvels: Science and Splendor at the Courts of Europe.” The Grünes Gewölbe said it would be closed Monday for “organizational reasons.”