As you can imagine, Chief, the local news stations have been giving this 24 hour coverage (it's on right now on all the local TV channels) including lots of overhead helicopter shots, and it appears as though the steel girder system holding the bridge up, just, for some reason collapsed.
And from the extensive video coverage here....including a video from a nearby business security camera actually showing the bridge collapse.....looks like a structural failure of the center span, which then pulled down the two end spans. You can see it here: http://www.cnn.com/
Latest casualty toll is 7 dead, 62 injured, and approx. 20 missing.
The bridge is a part of Interstate 35 which runs from the Canadian border near Duluth, MN to the Mexican border in Texas. I've driven over it many, many times.
It happened at 6:05 pm local time.....just toward the end of the evening rush hour, when the bridge was full of bumper-to-bumper traffic, and witnesses on the bridge said they were only going about 10 mph.
Lots and lots of tales of individual heroism.....those who were uninjured or lightly injured helping those who were in more serious condition....and lots of people who lived nearby scrambling down the maze of twisted girders to help pull people out of cars, trucks, and a school bus (with 60 kids on board), and give what care they could to the injured until the Emergency Services arrived.
Emergency Services from Minneapolis and St. Paul and nearby suburbs and counties were on the scene quickly, and, in the early stages, many, many civilian volunteers helped direct traffic, and carry the victims to waiting ambulances.
Luckily, nearby Hennipin County Medical Center is a Level One Trauma Center, and Northwest Memorial Hospital (also near to the scene) has an excellent Trauma Unit. Most of the injured were taken to those two facilities.
There are probably a number of cars underwater and more victims under the collapsed part of the bridge, so toll will climb as these are discovered.
Only a thorough investigation of the bridge will determine what actually caused the collapse and will answer all of the questions out there, but there was no local earthquake, and it doesn't seem that terrorism was involved.