The luckiest man in Krasnogorsk was evidently late for the concert and didnt get in since the terrorists were already there:

The luckiest man in Krasnogorsk 🇷🇺 was evidently late for the concert and didn’t get in since the terrorists were already there: “Holy crap, they’re running around in there with machine guns!!” The video is captioned with: “Oh my God, my curiosity almost killed me.” Source: NinaByzantina