The woman with a baby, and two girls, all carrying explosives, struck a crowded market in the town of Madagali 11 days ago, killing six people and injuring 17, according to the chairman of Madagali local government, Alhaji Yusuf Mohammed.
Small girls stage suicide attack at market in Nigeria
Nigerian army spokesperson Rabe Abubakar could not confirm that a baby had been used in the attack, and said the woman may have just been disguised to appear as if she was carrying an infant.
The UN children's agency (UNICEF) said it was the first such incident involving a baby reported in northeast Nigeria. "We are extremely worried about the use of a baby in this callous way," UNICEF spokesperson Doune Porter told the Thomson Reuters Foundation.
The suicide bombings, which bore the hallmark of militant group Boko Haram, are common in northeast Nigeria, the heart of the militants' seven-year campaign to create an Islamic state.
The militant group preys on displaced children or young girls it kidnaps and forces them to become bombers, with some unaware they are carrying explosives, aid agencies say.
The use of children as suicide bombers by Boko Haram has surged almost five-fold since 2014, with 19 child bombings, most involving young girls, recorded by UNICEF last year.
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Prior to the Madagali bombings, the youngest child used in such an attack was a nine-year-old girl, the UN agency said. The attack in Madagali is one in a series of bombings in Nigeria northeast, mainly Borno state, in recent weeks as Boko Haram steps up attacks with the end of the rainy season facilitating movements in the bush.
However, risk management consultancy Signal Risk's director Ryan Cummings said Nigeria's civilian joint task force (CJTF) had stepped up efforts to spot and search suspected bombers. "Several attempted attacks by females bombers have been thwarted (due to the CJTF), limiting casualties," he said.
Army spokesperson Abubakar said security forces would be extra vigilant and ready to respond to any new strategies used by Boko Haram. The militants' insurgency has killed about 15,000 people and forced more than two million to flee their homes.
In early 2015, the militants controlled an area the size of Belgium but has been pushed out from most of territory by the Nigerian military with help from neighboring countries.
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