Hope the authorities will catch the culprits.

The two bombs that killed three people and  injured at least 176 at the Boston Marathon on Monday were made from six-liter  pressure cookers crammed with shards of metal, nails and ball bearings and  stashed in black backpacks, police sources revealed today.

The cruelly-designed bombs have 'frequently'  been used in Afghanistan, India, Nepal and Pakistan, according  to a 2010 Homeland Security Department pamphlet - hinting at the origins of the bombers behind the worst terrorist atrocity in  the U.S. since 9/11.

When the devices exploded near the crowded  Boston Marathon finish line around 2.50pm on  Monday, victims suffered as many  as 40 shrapnel wounds each and at least 10 people needed amputations.  Witnesses described seeing  body parts  flying through the air and shoes that 'still had flesh in them'.

Sources added to CNN that a timer was likely  used to activate one of the bombs.

Although no group has yet claimed  responsibility for the attacks, similar devices were used in the failed 2010  attempt to bomb Times Square by Faisal Shahzad, who admitted he had undergone bomb-making training at a militant  Islamist faction camp in Pakistan.

A pressure-cooker bomb is also a preferred  weapon of al-Qaeda and listed as the 'most effective' weapon of jihad, according  to an English-language terror magazine called Inspire.

Read more: http://www.dailymail.co.uk/new...e.html#ixzz2QePx2V5u

Boston bombings: Obama condemns 'act of terrorism

US President Barack Obama has condemned the bombings at the Boston Marathon as a "terrorist act".

He said the attack had been a "heinous and cowardly act", but said it was not yet known who carried out the attack and why.

The FBI has said there are "no known additional threats" beyond the two bombs which went off.

Three people were killed, including an eight-year-old boy, and more than 150 injured by the bombs.

Doctors treating the wounded have said a number of people have had pellets and "nail-like" fragments removed from their bodies.

"Any time bombs are used to target innocent civilians it is an act of terrorism", said Mr Obama, who in his first briefing on Monday had refrained from referring to terror attacks.

He stressed that it was not yet known whether an organisation - either domestic or foreign - or a "malevolent individual" was responsible, nor what the motive might have been.

"Everything else at this point is speculation," he said.

"It will take time... but we will find whoever harmed our citizens and we will bring them to justice," he said.

The president praised the emergency services and members of the public who responded to the blasts, and said: "The American people refuse to be terrorised."

Two devices

The first of the explosions went off close to the marathon finish line at about at 14:50 local time (18:50 GMT) on Monday.

Seconds later, as rescuers were rushing to help the injured, another explosion went off nearby.

There had been reports that other suspected devices were found in the area, but speaking in Boston on Tuesday, the governor of Massachusetts, Deval Patrick, said it was "important to clarify that two, and only two, explosive devices were found yesterday".

Mr Patrick said all other suspect parcels had been examined and found not to be bombs.

Richard DesLauriers, the FBI agent in charge of the investigation, told reporters there was no longer any "known imminent physical threat" in the city.

He said the FBI was "not aware of any threat information prior to the marathon".

Police had received "voluminous tips" from the public since the bombings, he said, urging people to co-operate with investigators.

"We will go to the ends of the Earth to identify the subject or subjects who are responsible for this despicable crime, and we will do everything we can to bring them to justice," he said.

Timothy Alban of the Massachusetts State Police appealed to members of the public to send in any footage they had from the day.

"There have to be hundreds if not thousands of photographs or videos or observations that were made down at that finish line yesterday. And they're sitting out there amongst everyone that's watching this event this morning," he said.

"You might not think it's significant but it might have some value to this investigation."

Officials have not confirmed how the devices were made, but doctors treating the wounded have said their injuries indicate that the bombs contained metal shards and other shrapnel.

George Velmahos, chief of trauma surgery at Massachusetts General Hospital, where many of the wounded are being treated, said some people had arrived with more than 40 shrapnel wounds.

"Many of them have severe wounds, mostly in the lower part of their bodies, wounds related to the blast effect of the bomb, as well as small metallic fragments that entered their body - pellets, shrapnel, nails," he said.

He said the bombs had probably contained "multiple metallic fragments", and that the hospital had carried out four amputations.

Child killed

Details of those killed have been officially released, but eight-year-old Martin Richard, from Boston, has been named as one of those who died.

His mother and sister were also injured as they waited for his father to finish the race.

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The BBC's Franz Strasser talks to runners beside the Charles River

The annual Boston Marathon this year had a field of about 23,000 runners and was watched by hundreds of thousands of spectators.

It is held on Patriots' Day, a Massachusetts state holiday which commemorates the first battles of the American Revolution in 1775.

Sunday's London Marathon - the next major international marathon - is to go ahead, with police saying they have well-rehearsed security plans.

But organisers have said they will hold a 30-second silence at the start as a mark for respect for those killed and injured in Boston

If investigators have a good idea whom they are looking for, they are not letting on. Instead they are emphasising the need for methodical evidence gathering - asking the public for photos and film from the marathon and continuing to examine what are being described as fairly crude bombs.

The fact that there were only two devices increases the chance the attack is the work of only one or a small number of individuals rather than a major organised, international conspiracy. What is less clear is whether this was domestic anti-government extremism - of the type seen in the Oklahoma City bombing in 1995 - or someone influenced by al-Qaeda.

The victims and the country as a whole want to know who was behind this attack and what motivated them. That answer may open up further difficult debates, but for the moment the priority remains finding those responsible as soon as possible.

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