'I saw crane debris flying and the helicopter in flames'
16 January 2013 Last updated at 09:11 GMT
Aaron Rogers, who witnessed a helicopter crashing into a crane at a building site in south London, has described the experience as "surreal".
He told the BBC that he was at Vauxhall bus station when he heard a bang, looked up and "saw bits of helicopter debris flying to the floor".
Police said they first received calls at 08:00 GMT and the London Ambulance Service said it was also at the scene.
Mobile phone footage filmed by Jose Gomez and Craig Dunne