Unidentified persons, expected to be Neo-Nazi vandals, uprooted 11 memorial plaques commemorating Jewish Nazi victims in the German city of Greifswald on Friday, the 74th anniversary of Kristallnacht, Die Welt newspaper reported.

The plaques were part of the Stolpersteine, meaning “stumbling blocks”, project by German artist Gunter Demnig, memorializing victims of the Nazi regime throughout Europe. Each plaque bore the name of a victim and was placed in front of their former home. The plaques were slightly elevated above the sidewalk so that passerby would stumble upon them.

Greifswald police chief Knut Abramowski called the vandalism a “vile crime,” and promised a 2500-euro reward for any information that lead to the capture of the perpetrators.

“I condemn this malicious attack in the strongest terms,” Die Welt quoted Abramowski as saying.

Several German politicians also voiced concern over act.

“It is particularly shameful when something like this happens exactly on the anniversary of Kristallnacht,” Norbert Nieszery, the chairman of Germany’s Social Democratic Party told the newspaper.

Secretary of the Christian Democratic Union parliamentary group Wolf-Dieter Ringguth called the attacks on the memorials an “irreverent desecration”.

This was not the first time vandals sought to desecrate the Stolpersteine project. In October, an unidentified individual smeared black paint over similar plaques in the town of Zossen.