A suicide bomber disguised in a school uniform detonated explosives at a high school assembly in Nigeria's northeastern town of Potiskum on Monday, killing 48 students, according to survivors, hospital officials and a morgue worker.

An earlier figure given by Reuters put the number of dead at at least 35.

No one immediately claimed responsibility for the attack in Yobe State, a territory that has been hit by Sunni Muslim Boko Haram rebels during a five-year insurgency seen as the main security threat to Africa's leading oil producer.

Soldiers rushed to the grisly scene on Monday, but were chased away by people throwing stones, angry at the military's inability to halt the insurgency that has killed thousands and driven hundreds of thousands from their homes.