The unidentified man was pictured among the hundreds of protesters who breached the building and forced Washington, DC, into a lockdown — sporting a shirt emblazoned with the name of one of the Nazi’s deadliest concentration camps during World War II.

The shirt included an image of a skull and crossbones, and had the inscription, “work brings freedom” — the German phrase, “arbeit macht frei,” that hung over the camp in German-occupied Poland, the Forward reported.

The image went viral on social media Wednesday, and sparked widespread outrage from Twitter users.

“Among the terrorists invading Capitol today was a man (left) wearing a sweatshirt saying, ‘Camp Auschwitz,’” historian Michael Beschloss posted on Twitter.