A bomb blast and gunfire shook an area around an Islamic boarding school in northern Nigeria on Sunday, leaving two of the alleged attackers dead and at least three others wounded, officials said. It was not immediately clear who was behind the blast in the city of Zaria, but Islamist extremist group Boko Haram has been blamed for hundreds of deaths as part of its insurgency in northern and central Nigeria. The boarding school is run by prominent Salafist cleric Awwal Adam Albani, known for outspoken criticism of Boko Haram. He was also arrested last year over a bombing and arms possession, but later released for lack of evidence. A number of buildings in the area were damaged in the blast and, according to a rescue worker at the scene, other unexploded homemade bombs were located. The school building sustained damage, including broken windows. The violence occurred in the hometown of Vice President Namadi Sambo and came a day ahead of commemorations marking 52 years of Nigerian independence, but there was no sign of a link. The rescue worker at the scene, who spoke on condition of anonymity, said security officers initially moved into the area on Thursday after receiving information that a Boko Haram hideout was located in the neighbourhood. There was an exchange of fire on Saturday night between gunmen and security forces in the same neighbourhood, another relief official said on condition of anonymity. The complex includes the school as well as a mosque. A relief official said the blast was caused by an improvised explosive device. Witnesses said it appeared the blast had gone off inside a house close to the school, destroying the building. “Two suspects were killed,” Shuaib said. “The innocent victims that were injured were taken to hospital.” The two suspects were shot by security forces, according to Shuaib. The rescue worker said at least three people were wounded.