https://www.youtube.com/watch?v=GmpA-fnxfWI
NASA officials have described the event as a “catastrophic anomaly” but have not pointed to a cause of explosion yet. NASA reports that the team did not experience any warning signs prior to launch that there would be a problem.
The Cygnus spacecraft atop the rocket was carrying 2290 kg (5050 lbs) of cargo for the International Space Station, including the Arkyd-3 satellite.