Police in Upper Austria province said the four Germans — two sisters and their partners, in their 20s and early 30s — went to the building on Saturday to lay white roses in its window recesses. They posed in front of the house for photos and one of the women gave the stiff-armed Hitler salute.
Patrolling officers noticed the group and took them to a police station for questioning. The woman said that she hadn't meant the salute seriously, but officers said they found a chat with the others on her cellphone in which they shared Nazi-themed messages and pictures.
Police said they were reporting all four to prosecutors on suspicion of violating the Austrian law that bans the symbols of Nazism.