A manhunt is underway after burglars broke into one of Europe's largest treasure collections and took off with jewelry reportedly worth over $1 billion. The daring heist happened inside the Green Vault at the Dresden Castle in eastern Germany Monday morning, German police said.

The thieves stole three historic jewelry sets, which contain 37 parts each, BBC News reports. Authorities and museum officials in Saxony are still trying to figure out how much exactly was taken.

Photo taken on April 9, 2019 shows the White Silver Room in the historic Green Vault (Gruenes Gewoelbe) at the Royal Palace in Dresden, Germany. Sebastian Kahnert / Getty

"We are talking here of objects of immeasurable cultural value," museum director Dirk Syndram said in a news conference. "It's almost world cultural heritage. There is nowhere else a collection of jewelry in this form, quality and quantity."

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Police said two robbers came in through a window, walked toward a glass vitrine, smashed it and left with the stolen jewels, including diamonds, rubies, emeralds and sapphires. German newspaper Bild estimated the cost to be worth more than $1.1 billion.

Marion Ackermann, director general of the Dresden state museums, said the "priceless" items "cannot be sold on the art market legally — they're too well known."

Saxony's Minister-President Michael Kretschmer, denounced the crime on Twitter. "Not only the state art collections were robbed, but we Saxons."

File photo of a woman looking at precious objects in the Jewel Room of the Green Vault State Art Collection in Dresden, Germany, in 2006. Norbert Millauer / Getty

"The treasures that can be found in the Green Vault and in the Residence Palace have been hard-won by the people in the Free State of Saxony over many centuries," Kretschmer tweeted. "One cannot understand the history of our country, our Free State, without the Green Vault and the State Art Collections of Saxony."

The Green Vault is one of the oldest museums in Europe, founded by the August the Strong, Elector of Saxony, in 1723. One of 12 museums that make up the famous Dresden State Art Collections, the vault is split into a historic and a newer exhibition. There are about 3,000 items of jewelry and other treasures decorated with gold, silver, ivory and pearl, according to the BBC.

Three rooms were destroyed during World War II, but the museum was restored and opened to the public in 2006.

The museum's most valuable jewel is safe. The 41-carat gem known as the Dresden Green Diamond is currently on loan to the Metropolitan Museum of Art in New York.