Ukrainian jet burns fiercely & crashes to the ground; Hit by Russia or mishap?

A Ukrainian fighter was shot down late Sunday evening, videos show the jet burning fiercely. Wreckage pics suggest the downed jet was a Sukhoi Su-27, Russian platforms, however, say it was a MiG-29. Exact cause unknown, 2 versions doing the rounds - was it a friendly fire mishap, or a Russian Su-30 took it down? Friendly fire mishaps - the firing of weapons from one's own forces, especially when resulting in the accidental death or injury of one's own personnel.