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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Most parts becoming dry. Sunny spells on Friday.
Outbreaks of rain tonight but drier and brighter tomorrow.
It includes the National Space Centre and the Guildhall.