A university in Nigeria's northern city of Kano has been rocked by gunfire and an explosion, which may have targeted Christian students.
An army spokesman said a number of people had been wounded and were being rushed to hospital, but it was not clear how many casualties there were.
Staff at Bayero University told the media, that the incident was still going on.
Reports said the explosion appeared to target a lecture theatre where Christian students hold services.
Soldiers and police had surrounded the university and were searching for the gunmen.
No group has said it launched the attack, but the Islamist militant Boko Haram group is active in Kano.