Sad day. Video looks like he had a bike run over his head, which sent his helmet flying off, although its hard to make out exactly where and what impacted. But either way it should be for the filmset of Final Destination and not real life.

RIP A truly talented rider.

Even though neither could do anything to avoid the accident, it must be weighing awfully bad on Valentino Rossi and Colin Edwards' minds being involved as something as horrific as that.

The sport has lost one of it's brightest talents.

Marco has this season been the shining light in a somewhat stale race series. It was an awful accident to see and was eerily similar to the accident that took the life of Shoya Tomizawa last year and Craig Jones a couple of years before.

Very Sad RIP Big fella, he was really pushing for results this year, shame.

They are both distraught as to what happened with them hitting Simoncelli on the track. An absolutely tragic situation.