An eerie Nazi time capsule containing brass knuckles, gas masks, and a portrait of Hitler uncovered in German floods clean up

• A man who cleaned his aunt's house following the German floods found a trove of hidden Nazi artifacts.
• It included a gun, brass knuckles, and a portrait of Hitler behind a plastered wall.
• Experts excavating the home have since collected 12 boxes of artifacts.

A German man who was cleaning a house after it was wrecked by a flood was left stunned when he found a trove of Third Reich artifacts hidden behind a plastered wall.

Sebastian Yurtseven was renovating his aunt's house in Hagen, Germany in the aftermath of severe floods that hit the region in July, resulting in the deaths of 190 people.

He was pulling off a rotten piece of plasterboard when he came across a foot-wide wall cavity behind it that housed crinkly old newspaper, dated 1945.

Read more: Photos show catastrophic damage in Germany caused by extreme rain and flooding

As he removed the newspaper out, he realized there were many more items in the hole including a revolver, gas masks, hundreds of letters, and a portrait of Adolf Hitler.

"I got goosebumps," Yurtseven told local media. "I didn't think it would turn into such a huge discovery."

Yurtseven also found Nazi documents from the National Socialist People's Welfare (NSV), which was a social welfare organization that provided childcare, healthcare, and medical services during Hitler's Third Reich.

Experts believe the artifacts were quickly tossed inside the cavity in April 1945 when American forces start marching into Hagen.

Archive manager Ralf Blank told the Frankfurter Allgemeine: 'This must have happened very hectically. Such hasty disposal operations are common but to actually be able to secure a find like this, that alone is a very exciting thing."

The systematic robbery of Jewish citizens by the Nazis was used to subsidize the NSV during World War II.

"We hope, for example, to come across files on the distribution of so-called Jewish furniture," said Blank. A recently published study shows that the then legal department of Frankfurt donated the assets of Jewish foundations to the NSV, among others, according to the Frankfurter Allgemeine.

Archivists and archaeologists excavating the home have since collected 12 boxes worth of items, including piles of gas masks and Nazi insignia.

Yurtseven and his aunt said they had no idea of the Nazi legacy behind the wall of their family house, which was purchased by the family in the 1960s.