Gunmen have attacked a teacher training college in the Nigerian city of Kano, with officials saying at least 13 people have been killed.
Students were seen fleeing from the city's Federal College of Education and at least one explosion was heard.
Another 34 people were injured.
It is not clear who was responsible, although suspicion will fall on militant Islamist group Boko Haram, which has been waging an insurgency in Nigeria since 2009.
One student told the BBC by phone he had seen 17 dead bodies at the scene.
In July, the city suffered a spate of five attacks in four days, one of which also targeted a college and killed six people.
In May 2013, Nigeria's President Goodluck Jonathan imposed a state of emergency in the northern states of Borno, Yobe and Adamawa, vowing to crush the insurgency.