A group of German tourists was arrested in Austria on Saturday after police observed them commemorating Adolf Hitler’s birthday by laying white roses in a window at the building where he was born, authorities announced. Four were detained in total, including a woman who was allegedly spotted raising her arm in a Nazi salute as she posed for a photo outside the building. Cops said they detained the group, which included two sisters and their partners, in their 20s and early 30s, to a local police station for interrogation. The woman behind the Nazi salute claimed she made the distasteful gesture as a joke, but further investigation revealed she’d texted pro-Nazi messages with others in her group. Austrian police said they’d report all four to prosecutors for violating a national law that bans all Nazi symbols. The building at the center of the drama, in the tiny village of Braunau am Inn, is currently being renovated to turn it into a police station—a move Austrian officials hope will deter other Hitler fans from using it as a place to celebrate their hate.