Details have emerged about some of the men suspected of carrying out the attempted bombings of Tube trains and a bus on 21 July in London.
FIRST SUSPECT: IBRAHIM MUKTAR SAID
Ibrahim Muktar Said
Ibrahim Muktar Said, 27, also know as Muktar Muhammad Said, is suspected of leaving the explosive device on the back seat of a number 26 bus, in Hackney, on 21 July.
He arrived in the UK in 1992 from Eritrea in east Africa as a child refugee, with his family.
Brought up in Stanmore, Middlesex, he attended Canons Hill school in Edgware, north-west London.
He was said to have been a devout Muslim, wearing Islamic dress and growing a beard.
Police are investigating whether he prayed at the Finsbury Park mosque, in north London, where radical cleric Abu Hamza al-Masri preached, or Brixton mosque, in south London, which the convicted shoe-bomber Richard Reid attended.
In November 2003 he applied to become a British citizen, and was given a British passport in September 2004.
Wayne Howard, who still lives in Stanmore, told BBC News he met Ibrahim at school in 1991.
Said's "broken English" meant he "struggled a bit" and asked for extra spelling and English language lessons, but he was "always good at sport" and played competitive cricket, football and basketball, Mr Howard said.
He shared a flat with Yassin Hassan Omar, the man suspected of the attempted bombing of a Tube train near Warren Street station on the same day.
Police began searching the flat on the ninth floor of the New Southgate tower block in north London on Monday.
He was arrested on Friday as police raided a flat on the Peabody estate in North Kensington.
SECOND SUSPECT: YASSIN HASSAN OMAR
Yassin Hassan Omar, 24, is suspected of the attempted bombing of a Victoria Line train, near Warren Street, on 21 July.
Yassin Hassan Omar
Police used a Taser stun gun when they arrested him on Wednesday morning in a raid on the Hay Mills area of Birmingham.
He arrived in the UK with relatives as a 12-year-old refugee from Somalia and in May 2000 was granted indefinite leave to stay in Britain.
For six years, Omar was the registered tenant of the flat in the New Southgate tower block being searched by police, and received up to £24,000 in housing benefit.
THIRD SUSPECT: RAMZI MOHAMED
Ramzi Mohamed is suspected of attempting to bomb a Tube near Oval.
He was caught on CCTV cameras on the passenger concourse at Oval station seconds before leaving the station by vaulting over a ticket barrier.
Police arrested him in a raid in west London on Friday afternoon, at the Peabody Trust housing estate in Dalgarno Gardens.
FOURTH SUSPECT: HUSSAIN OSMAN
Hussain Osman is alleged to be the attempted bomber at Shepherd's Bush Tube station, and was arrested in Rome on 29 July.
Mr Osman was arrested at his brother's apartment in a middle-class neighbourhood outside Rome's historic centre.
He was originally said by the authorities there to be a Somali who is a naturalised British citizen.
However they later corrected this to say the 27-year-old was naturalised British subject of Ethiopian origin and had lied to obtain a British passport.
He may also be known by the name Hamdi Issac.
Italian officials confirmed that he had previously lived in Italy. When he was arrested, he had an old residence permit, which had expired in 1996, they said.
Authorities in Rome said he travelled by train from London's Waterloo Station on 26 July, with reports indicating his journey to Rome took him through Paris and Milan.
Italian police tracked him by monitoring his mobile phone calls, including calls in Milan and Brescia, where his father lives, and finally to Rome.
He faces extradition to the UK.
Mr Osman's wife, Yeshiemebet Girma, 29, and sister-in-law, Mulumebet Girma, 21, have been charged with failing to disclose information about him.
The sisters, both of Stockwell, appeared at Bow Street Magistrates' Court on 5 August.