BERLIN (AP) — A young man was severely injured Sunday when he fell off a slab that's part of the German capital’s memorial to the 6 million Jews killed in the Nazi Holocaust.

The 21-year-old tourist, whose name was not released in line with German privacy rules, fell several meters (feet) early Sunday and was taken to the hospital with head injuries, the German news agency dpa reported.

Police were still investigating the cause of the accident, dpa reported. Local Berlin media said the young man was an Italian tourist who had underestimated the height when jumping off the slab, which was in an unlit part of the memorial.

The memorial, a field of 2,700 gray concrete slabs near the Brandenburg Gate that opened in 2005, is open around the clock. Visitors are supposed to refrain from activities such as running and jumping from one slab to another.

Earlier this month, Berlin's police chief apologized for an incident in which officers were pictured practicing push-ups on part of the memorial.