The last two times we brought up heavy metal in Russia, it was because religious extremists were shutting shows down (see: Belphegor and Cannibal Corpse.) Thankfully for Bullet for My Valentine fans, their show was not shut down, but it could've led to something much more dangerous.
Some fans at the band's St. Petersburg, Russia gig took it upon themselves to start a bonfire inside the venue the band were performing in. It looks like things got under control very quickly:
Seeing something like this immediately brings my mind to the tragedy a few years ago at the Great White concert, or the club fire late last year in Romania that left almost 50 dead. Bullet for My Valentine have commented on the situation posting the above photo on their Instagram page, with a caption politely asking fans never to do that again:
We didn't need to bring pyro for this show as the crowd brought there own! Mental. (P.S this is very dangerous and as awesome as it looks please don't bring flares to shows as it could have ended up pretty bad). .
It seems pretty common sense – don't start a fire in a crowded area with possibly poor ventilation. An indoor metal concert is not the place to start a bonfire. Leave those for outdoor festivals (or better yet, just don't!)