The memorial site at the Auschwitz-Birkenau concentration camp in Poland was briefly closed on Friday due to an unusual incident, where a group of about a dozen protesters slaughtered a sheep, lit a fire, took their clothes off and chained themselves to the famous “arbeit macht frei” ("work sets you free") gate.

>> Get all updates on Israel and the Jewish World: Download our free App, and Subscribe >>

The protesters also draped a white banner emblazoned "love" over the famous sign. A spokesman for the Auschwitz memorial said the protesters' motives were not clear, but some reports suggested that the group was protesting against the armed conflict in Ukraine.

The group reportedly used a drone to film the disturbance.

The museum said the guards ordered the group to dress and alerted the police. The site was temporarily shut down and the museum intends to file a formal complaint with the prosecutor’s office. A police officer on duty, Grzegorz Babiuch, told reporters the group of young people was detained for questioning.

“The police [are] investigating the case,” the museum said in a statement, adding that visitors could return to the site after their work is completed.

“Using the symbol of Auschwitz to any kind of manifestation of happenings is outrageous and unacceptable. It is disrespectful to the memory of all the victims of the German Nazi Auschwitz concentration camp,” the statement said.

During World War II the Nazis killed some 1.1 million people at Auschwitz, mostly Jews.

With reporting by the Associated Press.