The london bombings where not not straight down. There was an initial selloff on the news that there was an explosion on the subway, but then the press started reporting that the explosion was due to a power surge, we saw huge short covering and initiation of longs on what appeared to be the press dispelling the notion of another terror attack. Then the explosions on the busses occurred and this is when the markets started to sink. Now there was no doubt that that another terror event had occurred.
The market sold off for 3 or 4 hours until the U.S. bond market opened and hasn't traded lower since. I think the DAX was down over 400 pts . Within this down move there were some bounces that took the markets off its low 50-80 pts a few times, before it eventually put in its low and rallied back.