you don't know until he goes to the hospital and gets checked out. when the care flight helicopter comes, that's as bad as it can get. >> the care flight helicopter rushes tommy to the closest trauma center. david, the driver who hit him, is uninjured and devastated about his friend. >> he was probably one of the most upset people there. i guess he felt like he might have been the cause of it or whatever. it actually, emotionally, scarred him to the point where he really lost the excitement and didn't want to get back in the race car again. >> the horrible accident leave spectators in shock and leads to a lot of second guessing and finger pointing among racing pros. >> it would be easier to say one of the drivers may have drove a little over his head or something, but we didn't see anything unordinary. it could have been parts failure, it could have been something that got underneath the tire. we really don't know. it happened so quick and so fast that it's hard to say exactly what happened. >> the cause of the crash was never determined. as for tommy, his stay at the hospital in houston is brief.