A blast rocked an area near a military barracks in the northern Nigerian city of Kaduna on Tuesday but the cause of the explosion and number of casualties were not immediately clear, an official said. \"NEMA rescue team alerted to explosion at military formations in Kaduna,\" National Emergency Management Agency spokesman Yushau Shuaib said in a brief statement. \"Yet to confirm the nature of explosion or casualty. Relevant security working to contain the situation.\" Residents said the explosion occurred in the area of a military barracks known as the First Mechanised Division and that windows in an office complex there were shattered. The area has been cordoned off, but the office complex could be seen, residents said. \"Virtually all the glass has been shattered,\" one resident said. \"I saw soldiers with glass cuts on their bodies being taken out, but it\'s difficult to say if there were any (more serious) casualties.\" Islamist group Boko Haram has been blamed for scores of bomb attacks in northern Nigeria. It claimed responsibility for January 20 coordinated bombings and shootings in Nigeria\'s second-largest city of Kano that left at least 185 people dead -- Boko Haram\'s deadliest attack yet.