A suicide bomber disguised in a school uniform detonated explosives at a high school assembly in the north-eastern Nigerian city of Potiskum, killing at least 48 students, according to survivors and a morgue attendant.
Soldiers rushed to the scene, grisly with body parts, in the capital of Yobe state, but they were chased away by a crowd throwing stones and shouting that they are angry at the military's inability to halt a five-year-old Islamic insurgency that has killed thousands and driven hundreds of thousands from their homes.
A suicide bomb attack in the same city killed 30 people one week ago, when suspected Boko Haram fighters attacked a religious procession of moderate Muslims.
Some 2,000 students had gathered for the weekly assembly at the Government Technical Science College when the explosion blasted through the school hall.
"We were waiting for the principal to address us, around 7.30am, when we heard a deafening sound and I was blown off my feet, people started screaming and running, I saw blood all over my body," 17-year-old student Musa Ibrahim Yahaya said from the general hospital.
Hospital records show 79 students were admitted and health workers said they include serious injuries that may require amputations. The hospital was so overcrowded that some patients were squashed two to a bed.
A morgue attendant said 48 bodies were brought to the hospital and all appeared to be between the ages of 11 and 20 years old.
Survivors said the bomber appeared to have hidden the explosives in a type of rucksack popular with students. Months ago Nigeria's military had reported finding a bomb factory where explosives were being sewn into rucksacks in the northern city of Kano.
Garba Alhaji, father of one of the wounded students, said the school did not have proper security.