His accomplices brought carnage to a Sufi shrine, but the 14-year-old suicide bomber who was captured after his explosives failed to detonate was unrepentant.

"Let me go, I want to be a martyr," he said as he was being led away, according to police officer Khalid Mahmood. "I want to send all you policemen to hell!"

The boy, identified as Fida Hussain, was arrested at the shrine in central Pakistan shortly after Sunday's twin suicide blasts, which killed 42 people and wounded 100 others. The complex close to Dera Ghazi Khan in central Pakistan was crowded with thousands of people attending an annual festival.

'Let me go, I want to be a martyr.'— 14-year-old bomber

Another suspect was also detained at the shrine, but police gave no details about him.

On Monday, a suicide bomber struck again, killing seven people at a bus station in the northwestern region of Lower Dir, said police officer Salim Marwat. One of the dead was a tribal elder who was regarded as pro-government, and as such was the likely target, he said.

Information from the pair detained at the shrine could provide clues about the network behind the blasts.

The shrine was targeted because Islamist extremists regard the veneration of Sufi saints — a much loved and widespread practice in Pakistan — as un-Islamic.

Mahmood said both boys were apparently from North Waziristan, one of seven tribally administered areas close to Afghanistan. All those areas are militant hotspots, but North Waziristan is considered especially so. It is under virtual militant control and is home to extremists from around Pakistan and the world.

Young boys, often with little or no education, are often used by the Taliban as suicide bombers. As well as being less suspicious, terrorism analysts say their handlers find it easier to persuade them to carry out suicide missions.

This suicide bomber was interrogated by security officials after his vest failed to fully detonate on Sunday. Other bombers killed 42 people in Pakistan on Sunday. (Saleem Raza Khan/Associated Press)

Mahmood said Hussain and the other attacker were at the shrine around for around one hour before striking. When Hussain's vest failed to detonate, he threw a grenade but it exploded close to him, blowing off his hand. Police then fired at him, hitting him in his other arm.

He was being treated for his injuries Monday, Mahmood said.

His comments to policemen offer a glimpse into the level of indoctrination he had received.

"You all are accomplices of the enemies of Islam who are bent upon eliminating Islam and Muslims," he allegedly said. "If I get a chance, I will again strike as a suicide bomber."

Taliban claims responsibility

In a brief phone call to reporters, a spokesman for the Pakistani Taliban, one of the country's largest and best organized militant groups, claimed responsibility. It is believed to be based in North Waziristan.

Followers of the Barelvi school of Islam, one of the two main branches of the religion in Pakistan, are most closely associated with the shrines and are seen as generally tolerant. The Deobandi school, of which the Pakistani Taliban mostly come from, regard worshipping at shrines as a deviation from Islam.

There have been at least five deadly attacks against similar shrines in Pakistan over the last two years.

While the attacks are motivated by religious differences, they also appear aimed at provoking sectarian warfare and making the government look weak because it is failing to protect the people.

The practice of visiting shrines is common among Muslims across South Asia, and those who do so insist they are not doing anything that contravenes Islamic law. The attacks on the complexes have caused anger, but many people - including educated, middle class Pakistanis, choose to believe in conspiracy theories that hold Americans or other non-Muslim, foreign powers responsible.