It is. I’m thinking it started at the moment of liftoff. It looks like a “minor” explosion in the first second or so after ignition.
https://www.youtube.com/watch?v=jHMmMgdcOSU
Higher quality video on this page:
http://kfor.com/2014/10/28/antares-rocket-crashes-upon-launch-from-wallops-island/
It will be interesting to get the ‘after-action report’ on this.
If there was an anomaly at liftoff, it was not evident to me, but then I’m not an expert (and the only rocket launch that I’ve witnessed in person was in 1978 at Vandenburg AFB, and I did not stay at a Holiday Inn Express last night).