Incorrect number

A powerful explosion wiped one of the pavilions of VDNKh off the face of the earth, where thirty young people - mostly ordinary Moscow students - had gathered for a private party. By all indications, what happened was a terrorist act, however, a number of circumstances make the investigation doubt this seemingly obvious conclusion. And then there are similar news from China, Europe, and both Americas that further complicate everything. Or maybe they explain everything? And was it just a coincidence that the pavilion mysteriously destroyed by terrorists was named 'Cosmos', while the club where those thirty unfortunate souls came for the opening was called 'Ark'? By the way, thirty is the right number. The wrong one is different...