AT least 15 Nigerian Muslim pilgrims on their way to Senegal were killed when gunmen in Burkina Faso attacked the buses transporting them, Nigeria's presidency said. "President Muhammadu Buhari has received the tragic news of the murder," the State House said in a statement without providing a number of casualties or further details on the attack. A Nigerian presidency spokesperson told Reuters via a WhatsApp message that the death toll stood at 15 "so far". According to a Senegalese religious order, unidentified assailants attacked the convoy of buses on Wednesday and killed 18 passengers. The pilgrims were on their way…