The West African Examinations Council (WAEC), building in the Yaba area of Lagos State was reportedly gutted by fire on Wednesday morning.
Some workers, who resumed at WAEC as early as 7:30am were already in their offices before the fire ignited.
The cause of the fire could not be ascertained but some officials attributed it to an electrical surge.
There was panic as the workers were led out of the building.
Some of the workers, it was learnt, were injured in the process of escaping from the building.
Emergency responders have been mobilised to the scene.