Nigerian school assembly hit by blast in Potiskum

At least 47 students have been killed by a suicide bomber at a school assembly in the north-east Nigerian town of Potiskum, police have said.

The explosion happened at a boys' science and technical school in the town. Police believe the militant group Boko Haram caused the blast.

It follows an attack on a religious procession in Potiskum a week ago.

Will Ross reports from Lagos.