Early Thursday morning, 124 headstones at a historic Jewish cemetery in Philadephia were found knocked over.

Johnny Gibson, the groundskeeper at Adath Jeshurun Cemetery for the last 44 years, arrived at the cemetery at roughly 6 a.m. and saw the damage. He told NBC Philadelphia, “The thought went through my mind, ‘This is a disgrace for somebody to do something like this,’” adding, “I don’t know who would do it. Were the people on drugs? Were they drunk? I don’t know. But you wouldn’t be in your right mind, I don’t think, to do something like this.”

Gibson said the vandals left no inscriptions or graffiti at the burial ground along Bridge Street in the city’s Frankford section. He explained that some of the graves at Adath Jeshurun date back to the 1850s, but few people use the cemetery for burials anymore.

Earlier in July, before he left for Europe on a business trip to bring Israeli business to his city, Philadelphia Mayor Michael A. Nutter signed a statement from American mayors urging mayors in Europe to publicly confront anti-Semitism. After he returned, he said, “Anyone who reacts negatively to me signing something like that, we probably don’t have much to talk about. So I’m pleased and proud to sign on.”