Dette melder BBC. Politiet fortsetter søk på andre adresser i hovedstaden. Om de fire arresterte er britiskfødte er foreløpig ikke kjent.
Four men are being questioned over an alleged terror plot after they were arrested in a series of raids by armed police officers across London.
The men – arrested at about 19:10 BST on Sunday in Whitechapel, Bayswater and Peckham – are being held on suspicion of the commission, preparation or instigation of acts of terrorism.
Searches are continuing at six addresses and on two vehicles.
Whitehall officials said the alleged plot was «potentially very serious».
But they said it did not appear to be on anything like the scale of earlier major plots, such as the airline liquid bomb plot or the Birmingham rucksack bomb plot, which resulted in convictions.
Two men, both aged 25, were arrested in a car in Mansell Street, Whitechapel, east London, after police fired «Hatton rounds» – ammunition designed to blow out tyres and blow open doors with minimal collateral damage.
A 28-year-old man was arrested at premises in Westbourne Grove, Bayswater, west London, and the fourth man, aged 29, was arrested in Peckham Hill Street, Peckham, south-east London.
BBC security correspondent Frank Gardner said the decision to make arrests was taken on Sunday by a joint committee of senior officers from MI5 and the Met Police’s Counter Terrorism Command.
As always, they faced a dilemma over whether to hold off longer to gather more evidence but then risk danger to the public, our correspondent said.
The alleged plot had been monitored for some time, he added.
George Paul, who saw the Bayswater arrest, said it had been «very dramatic, like the movies».
«What I saw was three policeman holding an individual down while he was shouting ‘please don’t break my arms’ or something of that ilk,» he told BBC News.
«They were basically trying to restrain him with another few officers ushering people away from the area.»
And Ramin Massodi, who watched the arrest from inside the Persian restaurant where he works, said: «I heard shouting; then I looked outside and saw four cars and they grabbed him.»
He said police officers pushed the suspect up against the glass of the restaurant.
Alistair Gillies, 38, who saw the same arrest, told BBC News he «noticed that a police car had pulled across the road».
«There was probably in the region of about two dozen officers. The majority of them appeared to be plain clothes but they had on baseball caps with the checkerboard and police marking. Apart from that, they were dressed in plain clothes,» he said.
«It didn’t look like they had just pulled a car over or had just picked someone up. It looked like there was a great deal of planning and a great deal of resources had been put on to tackling this situation.»