Sarah-Beth Casey, who had three small children with her in her apartment, saw the immediate aftermath of the helicopter crash.
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. I can't see any people on the ground, it seems to be a lucky escape. The police and ambulance response was incredible.
More top news
The Prime Minister has praised the former soldier's "huge professionalism" in trying to save the life of Pc Keith Palmer.
The man who carried out the Westminster attack is thought to be British born and was once investigated by MI5, the Prime Minister has said.
Jason Day, who lost his father to stomach cancer at the age of 12, broke down in tears as he explained his shock exit during the WGC event.