Richard Norton-Taylor, Guardian security editor
One thing is clear about this afternoon's events: the bombers and bomb makers were very different from the suicide bombers whose attacks exactly two weeks ago killed more than 50 people.
First indications suggested those responsible for today's attacks were "amateurs" and their bombs were crude. There is a report for example, that one of the devices was a nail bomb.
This time, the police have more evidence to help them in their investigations. The devices themselves, for a start. There are reports as I write that the police have captured the bomber at Warren Street, or chased him into a nearby hospital. There also should be valuable evidence from CCTV cameras.
This could be good news, if it provides important information. It might help the police and MI5 fill the huge intelligence gap that the July 7 bombings so clearly showed existed.
But so many questions remain. Were they copy-cat bombers? Were the targets chosen in the form of the four points of the compass - north, south, east, west, like the July 7 bombs were supposed to be?
Members of the public reported problems on the tube lines hours before the attacks. Was there prior intelligence of possible attacks?
The answers to these questions should be forthcoming rather more quickly than those we still await from the July 7 explosions.
