User blog comment:ShyGuyMapping/== ST PETERSBURG TERRORIST ATTACK ==/@comment-29401815-20170403151108/@comment-26865094-20170403153055

Probably just a young lost man who is fed up of life and wanted to kill. I would say it's possibly not ISIS since it wasn't a suicide attack like usual, but it could still be either a Chechen or a Dagestani, or maybe a even right-wing extremist or just a complete madman