Smoke rises in central London after a helicopter hit a crane on top of one of Europe's tallest residential blocks on Wednesday, killing two. Amateur video captures the scene of the unoccupied luxury high rise and damaged crane. Nine people below were injured, one other critically. More amateur video uploaded onto Youtube shows burning debris strewn down a street. London mayor Boris Johnson briefed a meeting of the London Assembly about the crash. (SOUNDBITE) (English) LONDON MATOR BORIS JOHNSON SAYING: "Many Londoners will already have seen the news that that there have been several casualties including two fatalities. As far as we can tell at the present time the emergency services have responded very fast and have done very well but but clearly our information is changing from moment to moment." Helicopters in London are generally supposed to fly along the River Thames but London City Airport said its flights had been disrupted due to poor visibility. The Department of Transport's crash investigation unit said it was preparing to launch an inquiry into the incident.