I work about 5 minutes from that bridge (at the U).. and have gone over it countless times..
My bestfriend was about to be driving over it, but decided to be nice and pick me up from work instead (exited the highway the exit right before the bridge, sat on the off ramp for ~10 minutes).. We drove on the bridge parallel to it at about 6:15 (6 minutes after it happened) and saw the destruction. It was pretty brutal.
We worked out the timing, and she would have been right over it, or within a minute (in bumper to bumper traffic) of either side of it.. Crazy shit.
People who were on the bridge when it happened said between 20-30 cars fell _into_ the river... I only saw a handful in the river, so they all sunk pretty fast.. None of those guys made it.