There are another nine parts to this footage as BBC World News continued to report on events throughout the day. It is also worth considering the effect of this "live" coverage and how much of it is recycled, as well as the conjecture presented on the part of the BBC and the reporters.
The fourth video is the BBC News at 10PM. Watch to see how a dramatic and ling winded event is compressed to fit the needs of the evening news audience. Also, consider how certain aspects of the reporting have changed, including the speculation about who is behind the attacks, etc.