British police have arrested 6 people suspected of preparing for terrorist attacks.
Some of the Thursday arrests took place near the Olympic site.
Three people were arrested in the east London district of Newham, which is within a few miles of the Olympic site, where the Games will open on July 27.
Police say the operation was not linked to the Olympics but was part of a planned intelligence-led operation.
According to a security source, the London arrests were related to international Islamist militancy and were made at an early stage of plotting.
It is not clear if any targets were identified.
Police say the six were arrested on suspicion of the "commission, preparation or instigation of acts of terrorism".
Neighbours describe how the police swooped upon the house in Newham in the early hours.
[Islam Hafizul, Neighbour]:
"Looked at the window, and I could just see the police entering the actual building. They actually, literally blew that door off, ripped it off actually, to get into the building. They had police around the back, police around the front. I was a bit wary of what's going on."
Another resident Darren Philips said he woke up to loud noises.
[Darren Philips, Neighbour]:
"I heard a big bang. Thought it was thunder at first, because it woke me up in my sleep. Then I heard the bang again. So I knew it wasn't thunder. Then it was followed by a round of shots from a smaller gun, so I knew there was some sort of activity going on outside. It was really, really loud."
Other arrests were made in west London.