Armed officers joined those from the counter terrorism command when the arrests were made at about 4am.
Police say the operation was not linked to the Olympics.
A 38-year-old woman was also arrested for alleged fraud offences and two other men were held over alleged immigration offences.
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The hunt for murder suspect Jed Allen has ended after police found his body two days after discovering his mother, stepdad and sister dead.
A woman who had been searching for her mother for more than 10 years has been reunited with her after posting an appeal on social media.
Although a dull start can be expected, it will brighten up in eastern areas. Especially to the south.