Aro Korol posted on Twitter: “Alarm at the US Embassy in London. They told us to move far from the windows. The situation is ongoing.”
Kelly Betts, who was queuing in the building said on Twitter she was told to “move away” but is still unsure what is happening.
A user called Roshan Kar wrote: “Situation ongoing at US Embassy London. Told us to stay away from the windows…”
Mr Korol shared a video of dozens of people say against a wall in the Embassy.
