Witnesses have described their shock at seeing a helicopter crash in central London after it hit a crane on top of a tower block by the River Thames.
Michael Krumstets and his flatmate were walking to work when "out of the blue, this happened".
He told Sky News: "We saw the helicopter hitting the crane at the top of the building and there was a loud crack, and then the helicopter started spinning out of control and incredibly towards us ... I mean directly towards us.
"We ran to the side of the road and it then crashed into the road just feet away from us and my flatmate fell over and I had to grab him but it was just awful.
"You see a helicopter hurtling out the sky towards you ... it's the last thing you expect on your way to work. And then it exploded.
"You see things like this in films ... of helicopters or planes crashing but when it's actually happening to you, it's coming towards you ... we were so lucky, we were just so lucky.
"We ran to the side of the road and we just managed to get away ... and then it hit the building on the side of the road and then it exploded ... by that point we were just shaken, you couldn't move ... what could you do?"
Commuter Patrick Garland also saw the accident unfold and told Sky News: "I was riding my bike in to work and was about 40 metres from the construction site when I heard a huge collision and a lot of shouting from workers on the site.
"I looked up and saw the helicopter having just crashed into the crane. Debris and rotors had sprayed everywhere and the helicopter had gone into large cyclical loops across Nine Elms and into the flower market.
"I watched what seemed almost like slow motion as it descended into the ground. There was not a large bang when it landed more of just thud and it simultaneously burst into flames.
"A huge plume of acrid black smoke rose and you could see the orange glow of the actual flames. The crane arm came crashing onto the road and there was debris falling everywhere.
"Myself and another cyclist scrambled for a bus shelter to avoid the falling debris. There was metal work (crane tubing and cabling and other building materials) raining down.
"We sheltered in the bus stop and there were workers running everywhere trying to stop traffic and congregate themselves near the building offices all very chaotic.
"It was a surreal experience and the whole scene just post crash was a scene of chaos and people seeming to not really believe what had just occurred."
Earlier, Sarah-Beth Casey, who lives in an apartment near the scene in Vauxhall, told Sky News: "I have three small children with me in the flat. It's one of your fears that something like this can happen.
"When I heard the explosion it was like a little earthquake. It was like a gas explosion. I looked up to see debris falling off the tower."
Matt Haverson was doing construction work on railway arches close to the crash site.
He said: "It was extremely scary ... I obviously thought it was a terrorist attack." Police have said there is nothing to suggest terrorists were involved.
Commuter Sherna Noah described seeing a "large plume of dark grey smoke" as she crossed Battersea Bridge at around 8am.
She said: "I was coming across the bridge and basically I could see a few cyclists on the bridge looking towards the water. I looked over to see what they were looking at and could see a pall of grey smoke coming from the south side.
"You could see a large plume of dark grey smoke."
People took to Twitter to report gridlocked traffic in the area, with emergency services struggling to get through