A suicide bomber blew himself up Thursday in a crowded market in northern Nigeria, killing six people, security sources said, blaming the attack on the Boko Haram jihadist group. The bomber, who passed himself off as a grain merchant, staged the attack in Amarwa village, about 20 kilometres (12 miles) from Maiduguri, the birthplace of Boko Haram and the capital of Borno State. The attack came days after a failed Boko Haram attack on Christmas Day in Maiduguri.