The one FSB mutt who was present for both the attack and the subsequent arrest clearly survived. So I’d imagine the rest of them did too.
As one of the commenters on YT pointed out the likely FSB agents in the crowd were remarkably calm considering there was a terrorist attack going on. Almost like they knew what was happening and that it was going according to plan.
Crazy question. You think it may have been done to sway public opinion? Anymore we live in a crazy world, anything is possible.