Matt Croydon has a good review of all the information available so far. Google News will most likely give even newer information.
At this time, we know that a shuttle that should have landed around 9:15am in Florida never reached its destination. However, 15 minutes prior to that time while the shuttle was about 150 miles south east of Dallas, TX, radio communication was lost and never regained. Various eyewitnesses have seen what they believe to be the shuttle in the sky and have reported multiple falling pieces. Due to the last known altitude of the shuttle, it is unlikely that the 7 crew members would have been able to exit the shuttle using the escape hatch.