Nigeria school assembly in Potiskum hit by blast

At least 20 students have reportedly been killed by a bomb at a school assembly in the north-east Nigerian town of Potiskum.

The explosion happened at a boys' science and technical school in the town.

Militant group Boko Haram is likely to be blamed for the attack.

It has often targeted schools during its five-year campaign to establish an Islamic state, which has left thousands dead.