Police have named two of the men they suspect of trying to set off bombs in a co-ordinated attack on three London Tube trains and a bus last Thursday.
Police are hunting Ibrahim Muktar Said (L) and Yassin Hassan Omar
Officers are seeking Yassin Hassan Omar, 24, and Ibrahim Muktar Said, 27. Said is linked to a property in north London, which is being searched.
The bombs were all placed in the same type of food containers and carried in dark rucksacks, police revealed.
Two more people have been arrested, taking the total number held to five.
The north London flat being raided by police is in Ladderswood Way, New Southgate.
Police said a number of other London addresses were also being searched.
Meanwhile, Deputy Assistant Commissioner Peter Clarke, of the Metropolitan Police, confirmed that a device found hidden in bushes near Wormwood Scrubs, west London, at the weekend was similar to those used by the four would-be bombers.
This device was also packed into the plastic food container, which is manufactured in India and sold in 100 outlets across the UK, he said.
Mr Clarke appealed to shop owners who may have sold five or more of the containers together in recent months to come forward.
They are described as six-and-a-quarter litre, clear, Delta family containers, with a white lid.
Mr Clarke, the head of the Met's anti-terrorist branch, urged anyone with information on the bombing suspects' whereabouts to immediately call 999 for emergency assistance.
"The public should not approach them," he warned.
WHO IS BEING HELD?
25 July - Second man arrested near Curtis House, north London
24 July - First man arrested near Curtis House
24 July - Man arrested in Tulse Hill, south London
22 July - Two men arrested in Stockwell, south London
In other developments:
An inquest opened into the death of Brazilian Jean Charles de Menezes, who police mistook for a suicide bomber at Stockwell Tube on Friday, heard he was shot eight times - seven times in the head and once in the shoulder.
It emerged the visa allowing Mr Menezes to stay in Britain had expired. In a news conference on Monday, Foreign Secretary Jack Straw said: "I haven't got any precise information on his immigration status, my understanding is he was here lawfully."
Mr Menezes' family say they may sue the Metropolitan Police over his death.
Tony Blair said he was "desperately sorry" about Mr Menezes' death but urged people to support the police in the "very, very difficult circumstances" they were facing.
Police said this man tried to set off a bomb at Oval Station
Police also have also given more details of the terror suspects' alleged movements on the day of the attacks.
Three of the men police want to trace entered Stockwell Tube station, in south London, just before 1225 BST last Thursday, Mr Clarke said.
The first suspect, as yet unnamed, but pictured above, attempted to set off a device between Stockwell and Oval stations, he said.
When this failed he was chased by "extraordinarily brave members of the public who tried to detain him", Mr Clarke explained.
He left Oval station at about 1235 BST and ran towards Brixton, discarding his distinctive New York logo top in Gosling Way as he went. He was last seen at 1245 BST in Tindal Street.
The second suspect, named as Said, took the Tube from Stockwell to Bank and then boarded a number 26 bus towards Hackney.
"He was carrying a grey and black rucksack and sat on a seat towards the back of the bus with the bag next to him. He too tried to set off a bomb," Mr Clarke said.
Police say Said might also be known as Muktar Mohammed Said.
The third man, who police named as Omar, entered Stockwell Tube carrying a small purple rucksack.
He allegedly tried to set off a bomb on a northbound Victoria line train between Oxford Circus and Warren Street stations.
Shortly afterwards, he was seen without the rucksack in Warren Street station, where Mr Clarke said he vaulted the ticket barrier and ran towards the exit.
A fourth man believed to be involved in the attacks got on a train from Westbourne Park station towards Shepherd's Bush, wearing a dark baseball cap and carrying a small rucksack.
After allegedly trying to set off his bomb, he got off the train, which was not below ground, probably by climbing through a window at the end of the carriage, police said.
He made his way along the track for 200 to 300 yards before making his way through back gardens, walking past BBC Television Centre in Wood Lane as he made good his escape, said Mr Clarke.
All journeys all started between 12:20
. Times approx.
1. OVAL: The first man got onto a Northern Line northbound train at Stockwell and attempted to set off a bomb between Stockwell and Oval at 1230 BST.
2. HACKNEY: The second man, identified by police as Ibrahim Muktar Said, or Muktar Mohammed Said, also started at Stockwell. At 1253 he got onto a Number 26 bus in the Bank area in the city carrying a bomb in a grey and black rucksack. He got off the bus in Hackney Road at 1306 BST. The driver heard a bang at 1330 BST.
3. WARREN STREET: A third man, identified by police as Yassin Hassan Omar, got on the Tube at Stockwell carrying a bomb in a purple rucksack. He later tried to set off the bomb on a northbound Victoria Line train between Oxford Circus and Warren Street. At 1240 BST he was seen without the rucksack in Warren Street Station.
4. SHEPHERD'S BUSH: The fourth man entered Westbourne Park Tube station and got on a train travelling towards Shepherd's Bush. At 1225 BST he tried to set off a bomb in his rucksack. It is thought he escaped by climbing through a window at the end of the carriage.