No explanation for the accident as of yet, though this is not the first incident associated with this breed of rocket.
You might have heard that a Russian rocket exploded soon after take off in Kazakhstan. The BBC reports that the Russian Proton M rocket was unmanned and carrying three satellites for Russia's Glonass satellite navigation system. The incident occurred near the Baikonur Cosmodrome space facility in Kazakhstan. Thankfully, nobody was injured, but the satellites on board the rocket were worth $200 million, and the LA Times cites RIA-Novosti news agency as saying work at Baikonur could be suspended for up to three months to clean up the fuel at the crash site.
If you haven't already seen it, you can check out the rocket's launch and subsequent explosion in the video below: