AFAIK it was actually shockwave from it's flight through the atmosphere. Which is quite scary because the energy should drop with something like squared distance, and the shockwave came from altitude around 55km. It could've weighed around 10 tons prior to entering atmosphere, but I guess only smaller lumps made it to ground.
Moar source:
https://rt.com/news/russia-meteor-meteorite-asteroid-chelyabinsk-291/