I heard a police helicopter an hour ago, then opened my Twitter to complain about the noise and found that:
(sorry for the lack of original pics, I wasted my chance to become a famous reporter and stayed at home)
First coverage from BBC is also available by this moment (and more).
My first idea about the reason of the riot was obviously that recent Ferry Lane shootup when supposed gangster was shot dead by police (BBC, local Indy).
Earlier anonymous witness told Evening Standard that the man was shot at point blank range pinned to the ground. I don't know if that's true and what exactly happened as there is no official release from Met yet (at least as far as I know) due to internal investigation launched, but anyway most likely that very information has triggered the rioting.
I believe things were not like that especially given the fact on which everybody seems to agree that the man shot first wounding an officer. Also, that place is usually crowded as a huge retail centre is just across the road plus buses to local IKEA stop nearby - so there should have been many people witnessing the operation, and only one stepped out with that version. Still, that information cannot be immediately discharged as total nonsense as the similar thing happened at least once.
So far no reports on wounded or injured people tonight, hope it stays like that.