Thieves broke into a documentation center at Adolf Hitler's one-time retreat in the German Alps near the town of Berchtesgaden early Friday, stealing a weapon along with Nazi-era badges and photos, police said.

Officers found a broken window at the Obersalzberg center when they arrived at the scene, alerted by the center's burglar alarm. Display windows inside the building had also been smashed and exhibits stolen.

Police in the nearby town of Traunstein declined to give details of the stolen weapon.

"We think this was a professional gang," spokesman Fritz Braun said. "A political background is not evident."

Hitler's haunt above the town of Berchtesgaden served as a part-time seat of government where he and other Nazi leaders often met to plan Germany's assault on Europe and the Holocaust.

Most of the Obersalzberg buildings were destroyed by Allied bombers in 1945.

The U.S. military used the area as a resort after World War II, before handing it back to Germany in 1996.

The documentation center opened in 1999.