An attack on a police station in northeastern Nigeria killed at least 12 people and wounded five others, authorities said Saturday, amid a growing wave of attacks by a radical Islamist sect. The assault on the capital of Gombe state targeted a divisional police headquarters and a federal prison there Friday night, local police commissioner Orubebe Ghandi Ebikeme said. Explosions could be heard across the city as sporadic gunfire continued into the night. The attack on the prison did not free any prisoners, Ebikeme said. Kayode Odeyemi, a spokesman for the Nigerian Prisons Service, said Saturday he had heard of the attack but had no details. It remained difficult Saturday to independently verify what had happened in Gombe, as the local government imposed a 24-hour curfew, forcing already frightened residents to remain indoors. Residents around the divisional police station said the area took heavy damage during the fighting. Authorities made no arrests and said that they had no immediate suspects. Suspicion, however, immediately fell on the radical sect known as Boko Haram.