The moment of the hit on the "Toronto" center in Kiev. 

Notice how hard it is to tell what hit the tower. If it was a Russian hypersonic or ballistic, the missile would be deafeningly loud, glowing from heat and look like a shooting star. It would be very hard to miss the moment of impact, yet in this video we can't even see what hit the tower. When you slow the video down to catch the moment of impact, the missile is small and moving slowly, neither of which fit the behavior of a telephone pole sized ballistic missile.  Another tell is that the warhead exploded into a field of shrapnel, which is how air defense missiles operate to maximize their hit chance.  

Judging from this video, the most likely scenario is a missed or failed air defense interceptor trying to protect the Luch design bureau HQ less than a KM away from this complex. If a Russian missile hit this building, it would be very obvious and would have done far more damage than this.