Suspect arrested after fire "completely engulfed" Hitler's Eagle's Nest mountain retreat in Germany

A suspect has been detained in Germany following a fire at Adolf Hitler's mountain retreat, known as Eagle's Nest, German police said.

Authorities were alerted to a fire at the Nazi leader's mountain residence on the peak of Obersalzberg at approximately 9:15 p.m. local time on Friday, Upper Bavaria South police said in a statement.

The building, also known as Kehlsteinhaus, was "completely engulfed in flames" when firefighters arrived, police said, but no one was found inside and no injuries were reported. 

Fire trucks had some difficulty accessing the site "due to the local conditions," authorities added.

"Shortly after the fire broke out, a suspect came into the focus of investigators," the statement said, adding that the cause of the fire is now under criminal investigation and one person was taken into custody.

At an elevation of 6,017 feet, Hitler's Eagle's Nest was completed in 1938 and occasionally used by the Nazi leader as a temporary seat of government. The site was spared from Allied bombing during World War II, largely preserving its original state.

Since then, it has become a popular tourist attraction, which also operates as a restaurant and beer garden. According to its website, the Eagle's Nest is "one of the few undamaged monuments of the Hitler era" and it "stands for the insanity of the regime."