Watch towers and the barbed wire fence of the former Nazi death camp Majdanek are pictured outside the city of Lublin in eastern Poland in this Nov. 9, 2005, file photo. Officials said Tuesday that a fire broke out overnight in one of barracks of Majdanek, destroying more than half of the building and up to 10,000 shoes of Holocaust victims.

Warsaw, Poland ? A fire swept through a barrack at the former Nazi death camp of Majdanek, destroying more than half the building and possibly 10,000 shoes of Holocaust victims, officials said Tuesday.

The Majdanek museum said the fire in the barrack housing a camp kitchen was discovered shortly before midnight on Monday by a guard making his rounds. The cause of the fire is not yet known and authorities are investigating.

In Israel, the director of the Yad Vashem museum, Avner Shalev expressed sorrow that the historic site and valuable artifacts had been damaged or destroyed.

“The damage to these irreplaceable items is a loss to a site that has such historical value to Europe, Poland and the Jewish people,” Shalev said.

Shalev offered assistance to the museum at the Majdanek camp, which is on the outskirts of Lublin in eastern Poland.

The museum said there were 10,000 shoes in the barrack, but that it was too soon to say how extensive the damage was.

Former death camps across an area once occupied by Nazi Germany are falling into a state of disrepair decades after the end of World War II. There have also been recent cases of vandalism at some of them.

The most brazen of those was the theft of the sign over the entrance gate at Auschwitz bearing the infamous slogan “Arbeit Macht Frei” — or “Work Will Set You Free.”

The thieves cut the sign in three pieces, but police quickly recovered it and arrested six suspects. A replica has since been put up in place of the original, which is being restored.

An estimated 80,000 people, including some 60,000 Jews, were killed at the SS-run Majdanek camp in occupied Poland between October 1941 and its liberation by Soviet troops in July 1944.