LONDON — He was barely old enough to drive in Britain. But last Saturday, Talha Asmal, a 17-year-old high school student from West Yorkshire, apparently detonated a Toyota Land Cruiser full of explosives at an Iraqi security facility and became his country’s youngest known suicide bomber.
Mr. Asmal left his family home over the Easter holidays, just a few weeks shy of his final school exams, and traveled to Syria to join the Islamic State militant group. After the bombing about 20 miles outside the northern town of Baiji, home to Iraq’s largest oil refinery, social media accounts linked to the group announced the attack and posted a series of images that also featured Mr. Asmal, whose nom de guerre appeared to be Abu Yusuf al-Britani. The attack involved four vehicles striking different security targets and killed at least 10 people.
The British Foreign Office has not been able to confirm that Mr. Asmal was one of the suicide bombers, a spokeswoman said on Tuesday. But members of his family in the West Yorkshire town of Dewsbury in northern England said in a statement that the bearded teenager in the Islamic State posts looked like their son.
Mr. Asmal’s parents described him as “loving, kind, caring and affable” and said they believed their son was radicalized on the Internet and in social media in the space of only a few months. They accused Islamic State leaders of cowardice for grooming their son to carry out their “dirty work.”
Like other Western countries, Britain has experienced the flight of hundreds of its young Muslims, many of them minors, to Syria, as schools and parents struggle to detect signs of a radicalization that often seems to happen largely online. Another recent case involved the departure of three schoolgirls from the Bethnal Green neighborhood in East London in February. Grainy security-camera images of the girls — ages 15 and 16 — confidently passing through airport security shocked the country.
Like the girls from Bethnal Green, Mr. Asmal did not go on his own. He traveled with a friend and neighbor, Hassan Munshi, also 17, and told his parents that he was going on a school trip, according to The Times of London. By the time the police issued an alert, it was too late: The two teenagers had already flown to a resort in eastern Turkey and then slipped across the border into Syria.
Mr. Munshi is nowhere to be found. Security officials say that the case of his older brother, Hammaad Munshi, may have contributed to the boys’ radicalization: He was convicted in 2008 at the age of 18 for his role in a plot to kill non-Muslims.
One of the images posted online by the Islamic State appears to show Mr. Asmal, wearing a black shirt and smiling broadly, standing next to a black Toyota with the Islamic State flag behind him. Another shows him sitting on the floor with an assault rifle on his lap.
Saad Maan, a spokesman for the Iraqi Interior Ministry, said the authorities were aware that the Islamic State, also known as ISIS or ISIL, had claimed responsibility for the attack and had asserted that one of the bombers was a Briton. But he said Iraqi investigators had not established the identity of the bomber. He said the group frequently used foreigners as suicide bombers.
If Mr. Asmal’s role in the attack is confirmed, he will be the youngest known British suicide bomber to date. Hasib Hussain, also from West Yorkshire, was 18 when he blew himself up on a London bus as part of the coordinated attacks of July 7, 2005.
The Islamic State often recruits boys even younger. The group has been aggressive in indoctrinating children in the parts of Iraq and Syria it controls, opening camps for religious instruction and military training and posting photographs and videos referring to the boys as “the cubs of the caliphate.”
Sometimes, young recruits are given a choice: Become a suicide bomber or a fighter. Last year, a 14-year-old boy from Syria who was wearing a suicide vest turned himself in to the authorities in Baghdad.
The Islamic State is not the only exploiter of children in the upheaval gripping the region. Many of the Shiite militias in Iraq, for instance, include boys of 14 or 15 in their ranks; so do Sunni tribal groups fighting on the government’s side. This year, at an event in Amiriyat Fallujah, in Anbar Province, where Sunni tribesmen were being inducted into a government program to combat the militants, some of the recruits were as young as 14.
Mr. Asmal’s family lives in the same mainly Muslim neighborhood of Dewsbury where the leader of the July 7 attacks, Mohammad Sidique Khan, once lived. But they said their son had never exhibited “any violent, extreme or radical views” before he left.
The executive principal of his school, Lorraine Barker, spoke similarly of him to The Times of London. The paper quoted Ms. Barker calling Mr. Asmal “just a conscientious student” and saying there was “no indication whatsoever” that he was on a path toward violent extremism.
A spokesman for the office of Prime Minister David Cameron called the case “deeply concerning” and said the government wanted to work with social media companies to stop recruiters from targeting young people online.
Shahid Malik, a former lawmaker for the Dewsbury district and a family friend of the Asmals, said it was “disturbing” to see Mr. Asmal appear “at peace” in the photographs that purported to be taken just before the suicide mission.
“This is a clear indication of just how successful the evil ISIS groomers have been in poisoning and brainwashing Talha and kids like him,” Mr. Malik told the BBC.
“Mosques need to confront this evil ideology head-on,” he continued. “I would say that, up and down the country, that is not happening at the moment.”
Prime Minister Haider al-Abadi of Iraq, speaking on Monday at a conference in Baghdad, said the Islamic State was “conducting an organized recruitment process of children” in more than 100 countries.
“Today, this organization is sending a message of fear and horror to the world,” he said. “One of their messages regarding childhood is to terrify us. They’re telling us, ‘Look — not just this generation, but also the next generation will be able to kill you.’ ”
The family’s statement suggested that the youth’s age and naïveté were “exploited by persons unknown who — hiding behind the anonymity of the World Wide Web — targeted and befriended Talha and engaged in a process of deliberate and calculated grooming of him.”
“As a result of this, and completely unbeknownst to us, his family, and entirely against our wishes, he ended up traveling, it seems, to Iraq,” the statement said, noting that “he was ordered to his death by so-called ISIS handlers and leaders too cowardly to do their own ‘dirty’ work.”
Standing out from the statement in bold text was this line: “ISIS. Not and never in our name.”