Police have disabled two car bombs in central London found to be loaded with nails and petrol. People living and working near the scene of the first discovery have described the scene.
Eye-witnesses sent their pictures of the empty streets
Officers carried out a controlled explosion after reports of a suspicious vehicle parked in Haymarket shortly before 0200 BST.
The area was cordoned off as forensic experts examined what they described as a "potentially viable explosive device".
Rajeshree Patel was in the Tiger Tiger club when the alert began. She told the BBC clubbers were ushered away from the front door when trying to leave the building.
"We actually thought we would use another exit, thinking there was some kind of skirmish. Then we found the backdoor was also blocked and we weren't able to actually leave.
"We were then slowly ushered out through the back entrance through another floor - because there are four floors - and it was only when we went out onto the street and tried to make our way to the front of the building that we realised it was all cordoned off."
THE LOCAL RESIDENTS
Local resident Angela Coster, who lives in Haymarket, said she found out about the bomb from television news.
"We're in a residential block in Haymarket - it seems strange that there's 18 flats in the block and not one person was woken up. It's kind of off-putting in a way," she said.
Ms Coster said a police officer could not tell her whether she would be able to return home after work.
"He had no idea whether we'd be able to get back in or not... if the blue tarp is still there I don't think I'll feel very safe," she said.
Alexander Aragon, who lives 100m from Tiger Tiger nightclub, where the suspicious car was found, decided to stay home after police told him that if he left his building he may not be allowed to return.
"Everything's dead quiet," he told the BBC News website. "The best way to describe it, like my wife said, is it's like the movie 28 Days Later."
He said police were patrolling the area, but by midday they had removed one of the cordons near his block.
Alan Bassett said that police had surrounded every exit to his apartment building as he left for work in the morning.
"No-one attempted to evacuate us out of the flat as far as I'm aware. They're very anxious not to let me go back into my flat now," he said.
"If I hadn't put the BBC on this morning I'd have had no idea what was going on at all."
Another eye-witness Sonja Bakkes said that most people in the area seemed "very blasť" about the situation.
"People are just having a look and obviously wanting to know how they can get to where they're going but everyone's very calm. No one's overly excited.
"Everyone's going to work as usual... I don't think people really know what's going on."
Robert Hoadley, who manages many of the landmark buildings in the area - including The Trocadero, London Pavilion and Lillywhites - told the BBC the bomb was found at a busy time of day in that part of town.
"This time of the morning you've got a lot of bus routes going down past there, I think the number 38 bus - one of the main bus routes into Victoria goes past there - so that's certainly where I saw the barriers up and the screens up from the back of the police cordon at the Lillywhites end of Jermyn Street," he said.
Yoo Na Lee, a tourist from Korea, was at the site with her boyfriend and was taking pictures of what she believed was a movie set.
"We thought a Hollywood star was here and it was a movie scene," she said. "We did not know it was the news."