He wrote about this on Facebook.
Butusov admits: "I do not think it was Tochka-U": VIDEO AND PHOTO of the EXPLOSION
A short range tactical ballistic missile Tochka-U is not so accurate weapon to be used to hit the city. The missile's probable deviation is up to 200 meters. The Soviet missile complex operational use standards charge to launch a salvo of four missiles to ensure straddling of the target. At the same time our missiles are out of date - they are already 30 years old and their operational life was extended yet back in 2011. There were cases of technical rejection of the missiles as well as spontaneous explosions soon after the launch when the 19th Missile Brigade conducted shooting. The missile's warhead weighs 500 kg. A remote fuse detonates it above the ground to blanket the area of up to one square kilometer. The main purpose of Tochka is to destroy vulnerable surface targets such as equipment accumulation, control units, communication hubs, warehouses, air defense systems. The missile would not destroy a certain protected object.
These missile systems cannot be used against targets within a city -the missile can easily miss the mark by a kilometer hitting a hectare of a residential neighborhood in this case.
Besides, the engine does not separate from the rocket and usually the tail part stays in the area of impact, so the missile could be successfully identified during search.
It seems that there was some act of sabotage or a technological accident at a fuel depot or energy facility with gas storage. This is evidenced by a pillar of flame. But the explosion was certainly of technological nature because any mine would give such a powerful shock wave that would expand to a distance of several kilometers. Something highly inflammable has detonated there. A manmade accident is quite likely because there is no government in Donetsk, no control, and no responsibility. And technology requires control but not chatter about "Novorossia".