Two members of the Russian precision aerobatic team, the Black Knights collided while practicing for the Moscow Airshow. Below is a video of one of the jets post impact. The smoke coming out of one engine is caused by compressor stalls. The tail section is on fire and the SU-27 is holding a constant negative g attitude. The streaks going up are the pilots ejecting. I suspect the aircraft was hit in the tail and the horizontal stabilizer control package failed causeing the negative g. The crews ejected (2 per aircraft), the team leader was killed. Little can be gleaned from the post impact video. However, if the leader was involved then it is likely that the wingman ran into him. The lead sets the pace and all others key off of him.