Loughborough MP Nicky Morgan says she "heard an almighty bang" and "saw clouds of thick black smoke" as the helicopter crashed into a crane in South London this morning.
The MP was walking towards Vauxhall tube station, when the accident happened.
"Ms Morgan says she "saw clouds and clouds of thick black smoke billowing from the ground" and that initial thoughts were that a bomb had exploded."
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A dry day across the region with bright or sunny spells after a frosty start. However, cloud will tend to increase from the west by evening.
After a cold, bright and frosty start, skies will gradually turn cloudier through the afternoon. However, it will stay dry with light winds.
An engineer has been confirmed dead in the crash in Wales. The RAF say the pilot survived and is receiving treatment.