An audacious burglary at one of Europe’s largest collections of treasure in the German city of Dresden saw thieves get away with at least 100 objects potentially worth more than $1 billion. The exact details of the operation, and what was taken, are not yet clear, but local news outlets report the thieves targeted the jewelry section of the historic Royal Palace after entering the building through a small window. Authorities said three diamond jewelry sets, consisting of as many as 100 pieces of diamonds, pearls, and rubies, were taken from the Grüne Gewölbe (or Green Vault) housed in the downtown palace in what’s believed to be the biggest treasure heist in the postwar era. “We can confirm that there has been a break-in in the Grüne Gewölbe,” a police spokesman said Monday. “The perpetrators are on the run.”

Police say they were notified by museum security personnel at 4:59 a.m. that a break-in was underway after spotting two suspects on CCTV. “The suspects came in through a window and walked towards a glass vitrine, smashed it and left, they disappeared,” the Dresden police chief said. The Dresden fire department responded to a fire in the early morning hours nearby the collection that initial reports say could have been a part of the heist. The fire knocked out the power to the palace museum, disabling the vault’s security alarm system. The thieves appeared on CCTV, but the power cut had plunged the vault into darkness making it difficult to identify the suspects. Authorities say a burning car was later recovered in the city and is believed to be the getaway car used by the burglars.

“The Grüne Gewölbe alone consists of 10 rooms teeming with about 3,000 items of jewellery and other recognised masterpieces,” the Guardian reports. “Treasures in the museum include a 63.8-centimetre figure of a Moor studded with emeralds and a 547.71-carat sapphire. One of its most famous and precious treasures, the Dresden Green Diamond, is currently on loan with other valuable pieces to the Metropolitan Museum of Art in New York for an exhibit.”