The Investigation: Police look for links between bomb attacks

Initial tests have revealed marked similarities between the devices used on both occasions and also evidence that it was only faulty detonators that prevented carnage yesterday. At least three of the men responsible for yesterday's attempted bombings were on the loose last night after fleeing the scenes.

Questions were raised about what appeared to be another failure of intelligence. The security agencies had been caught out by the 7 July bombings which, Home Secretary Charles Clarke admitted, "came out of the blue". Yet yesterday bombers with rucksacks, just like last time, managed to get to their targets undetected.

And yesterday was the day that the Prime Minister met senior officials from the police, MI5, MI6 and GCHQ (the Government's listening-post) in what was in effect an inquest into what went wrong two weeks ago. But police and the security agencies stress that this time they have crucial advantages lacking in the previous bombings. Unexploded devices will yield vital forensic clues. The Metropolitan Police Commissioner Sir Ian Blair said: "We believe this may represent a significant breakthrough."

Sir Ian added that the attempted blasts on three Tube trains and a bus, a copy of the 7 July attack, "must have been to kill". He said he was not in a position to state whether the two attacks were connected, but he added: "There were four attacks and there were four attacks before. We can all see that the attacks have a similar pattern."

Detectives are waiting to question a man believed to have been injured in the attempted attack at Warren Street. Witnesses said they saw a man running into the nearby University College Hospital. Armed officers entered the hospital and after 4.20pm a police convoy left at high speed with motorcycle outriders.

Two men were arrested in the afternoon, including one at Whitehall, who was ordered to the ground by armed police. But police said that they were not linked to the attacks.

Passengers who had streamed out of the trains and the No 26 bus at Hackney Road, in Shore ditch, east London, were corralled by police into makeshift interview areas for statements and to check whether they had taken any images with their mobile telephones. Officers also began to study CCTV footage.

Unlike the 7 July bombings, by suicide bombers prepared to sacrifice their lives, the terrorists yesterday abandoned their bombs and fled, pursued at least on one occasion by passers-by.

The detonators on at least two of the devices are believed to have initiated but did not ignite the explosive in the rucksacks. One did not detonate at all, and another only partially. In all four, the main charges were not detonated. Sir Ian refused to confirm or deny reports that the devices were packed with nails and shards of metal.

It is still unclear what type of explosive was used in the bombs. One of the key questions is whether the material used in the explosive is the same homemade material used in the bombs of 7 July. Police are still struggling to discover the make-up of the explosive used two weeks ago, but it is thought to be of a type similar to material known as the "Mother of Satan", triacetone triperoxide or TATP. The base ingredients - drain cleaner, bleach and acetone - can be bought easily without attracting suspicion; its chemical composition is simple, and in its finished form it is almost undetectable by sniffer dogs or conventional bomb-detection systems.

The detonators used in yesterday's attack appear to be the weak point. Andy Oppenheimer, an explosives expert with Jane's Information Group, said the "popping" sound heard by witnesses could indicate the explosion of a detonator.

"That would be a typical sound that would be heard, a dull thud. This type of malfunction used to happen to the IRA, who had expert bombmakers. It could be bad workmanship or it could be a deliberate attempt to disrupt the city two weeks later."

There had been reports that the staff at University College Hospital had been told to look out for a man of black or Asian appearance wearing a blue top who had run into the hospital. But this was later denied by hospital authorities.

However, three rooms in an unoccupied part of the hospital remained cordoned off last night. In a statement, the hospital said: "Police have confirmed that there is no danger to patients or staff. Armed police conducted a search of the hospital this afternoon and this has been completed. Three small rooms in an unoccupied part of the hospital have been cordoned off and police inquiries are still continuing.

"We are cancelling routine appointments and surgery tomorrow for patients not already in the hospital.''

Robert Naylor, the hospital trust's chief executive, said: "Our first priority has been the safety of patients and staff. Throughout this afternoon we have worked closely with the police in their investigations while maintaining emergency services."

* The hunt for members of the terrorist cell behind the 7 July bombings was mired in confusion last night after it emerged that no one had been arrested in Pakistan in connection with the London attacks. The British high commissioner in Islamabad rejected claims that the "al-Qa'ida mastermind" of the attack had been captured.

Life and Style
tech
Sport
Farah returns to the track with something to prove
Commonwealth games
News
John Barrowman kisses his male “bride” at a mock Gretna Green during the Commonwealth Games opening ceremony
peopleBarrowman's opening ceremony message to Commonwealth countries where he would be sent to prison for being gay
Voices
voicesGood for Lana Del Rey for helping kill that myth, writes Grace Dent
News
ebookA unique anthology of reporting and analysis of a crucial period of history
Sport
Shinji Kagawa and Reece James celebrate after the latter scores in Manchester United's 7-0 victory over LA Galaxy
football
Arts and Entertainment
The Tour de France peloton rides over a bridge on the Grinton Moor, Yorkshire, earlier this month
film
Life and Style
fashion Designs are part of feminist art project by a British student
News
Very tasty: Vladimir Putin dining alone, perhaps sensibly
news
Life and Style
Listen here: Apple EarPods offer an alternative
techAre custom, 3D printed earbuds the solution?
Arts and Entertainment
Top guns: Cole advised the makers of Second World War film Fury, starring Brad Pitt
filmLt-Col Steven Cole is the man Hollywood calls when it wants to borrow a tank or check a uniform
News
Snoop Dogg pictured at The Hollywood Reporter Nominees' Night in February, 2013
people... says Snoop Dogg
News
The University of California study monitored the reaction of 36 dogs
sciencePets' range of emotions revealed
Arts and Entertainment
A scene from Shakespeare in Love at the Noel Coward Theatre
theatreReview: Shakespeare in Love has moments of sheer stage poetry mixed with effervescent fun
News
Joining forces: young British men feature in an Isis video in which they urge Islamists in the West to join them in Iraq and Syria
newsWill the young Britons fighting in Syria be allowed to return home and resume their lives?
Arts and Entertainment
The nomination of 'The Wake' by Paul Kingsnorth has caused a stir
books
Latest stories from i100
Have you tried new the Independent Digital Edition apps?

Day In a Page

Screwing your way to the top? Good for Lana Del Rey for helping kill that myth

Screwing your way to the top?

Good for Lana Del Rey for helping kill that myth, says Grace Dent
Will the young Britons fighting in Syria be allowed to return home and resume their lives?

Will Britons fighting in Syria be able to resume their lives?

Tony Blair's Terrorism Act 2006 has made it an offence to take part in military action abroad with a "political, ideological, religious or racial motive"
Beyoncé poses as Rosie the Riveter, the wartime poster girl who became a feminist pin-up

Beyoncé poses as Rosie the Riveter

The wartime poster girl became the ultimate American symbol of female empowerment
The quest to find the perfect pair of earphones: Are custom, 3D printed earbuds the solution?

The quest to find the perfect pair of earphones

Earphones don't fit properly, offer mediocre audio quality and can even be painful. So the quest to design the perfect pair is music to Seth Stevenson's ears
US Army's shooting star: Lt-Col Steven Cole is the man Hollywood calls when it wants to borrow a tank or check a military uniform

Meet the US Army's shooting star

Lt-Col Steven Cole is the man Hollywood calls when it wants to borrow a tank or check a military uniform
Climate change threatens to make the antarctic fur seal extinct

Take a good look while you can

How climate change could wipe out this seal
Should emergency hospital weddings be made easier for the terminally ill?

Farewell, my lovely

Should emergency hospital weddings be made easier?
Man Booker Prize 2014 longlist: Crowdfunded novel nominated for first time

Crowdfunded novel nominated for Booker Prize

Paul Kingsnorth's 'The Wake' is in contention for the prestigious award
Vladimir Putin employs a full-time food taster to ensure his meals aren't poisoned

Vladimir Putin employs a full-time food taster

John Walsh salutes those brave souls who have, throughout history, put their knives on the line
Tour de France effect brings Hollywood blockbusters to Yorkshire

Tour de France effect brings Hollywood blockbusters to Yorkshire

A $25m thriller starring Sam Worthington to be made in God's Own Country
Will The Minerva Project - the first 'elite' American university to be launched in a century - change the face of higher learning?

Will The Minerva Project change the face of higher learning?

The university has no lecture halls, no debating societies, no sports teams and no fraternities. Instead, the 33 students who have made the cut at Minerva, will travel the world and change the face of higher learning
The 10 best pedicure products

Feet treat: 10 best pedicure products

Bags packed and all prepped for holidays, but feet in a state? Get them flip-flop-ready with our pick of the items for a DIY treatment
Commonwealth Games 2014: Great Scots! Planes and pipers welcome in Glasgow's Games

Commonwealth Games 2014

Great Scots! Planes and pipers welcome in Glasgow's Games
Jack Pitt-Brooke: Manchester City and Patrick Vieira make the right stand on racism

Jack Pitt-Brooke

Manchester City and Patrick Vieira make the right stand on racism
How Terry Newton tragedy made iron men seek help to tackle their psychological demons

How Newton tragedy made iron men seek help to tackle their psychological demons

Over a hundred rugby league players have contacted clinic to deal with mental challenges of game