BBC News reports a suicide bomb attack has killed at least 15 people at a bus station in north-eastern Nigeria, witnesses told BBC News. Two bombers were apparently involved in the attack in Biu There are also unconfirmed reports of an attack on a bus station in another town, Jos. Violence by Boko Haram Islamist militants in the region has already led to the postponement of February's presidential election. The vote will now take place on 28 March. President Goodluck Jonathan, who was visiting the north-eastern garrison town of Baga, insisted that the army was winning the war against Boko Haram. The army recaptured Baga from Boko Haram last week. The group still controls much of the north-eastern state of Borno and more than three million people have fled their homes.