A bomb blast which detonated in the middle of a school assembly in Yobe State was carried out by a suicide bomber disguised in school uniform, according to survivors.
The attack, which took place in the north-east Nigerian town of Potiskum, killed at least 48 students and wounded 79 people, police spokesman Emmanuel Ojukwu and a morgue attendant confirmed.
It is believed that the suicide bomber hid the explosives in a rucksack that many students wear.
When soldiers arrived at the scene of the bomb attack, they were chased away by angry civilians with stones - evidence of the anger people feel at the Nigerian government and military's inability to prevent Islamist attacks against civilian attacks in the country's north-east regions.
Approximately 2,000 students had amassed for the weekly assembly at the Government Technical Science College when the bomb detonated in the school hall, survivors told the Associated Press on condition of anonymity.
"We were waiting for the principal to address us, around 0730, 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 a nearby hospital.
The morgue attendant who confirmed the 48 casualties said that all of the bodies were between 11 and 20 years old.
There has been no claim of responsibility from Islamist group Boko Haram yet but suspicion has been placed on the group because of its insurgency in Nigeria's north-eastern regions and its numerous attacks on education institutions.
Boko Haram stands for "Western education is forbidden" and the group have continuously carried out attacks to prevent children attending school. In April, the group sparked international condemnation after kidnapping over 200 schoolgirls from a boarding school in the village of Chibok.
The state of Yobe has been placed under a state of emergency as well as the states of Borno and Adamawa because of the group's campaign of terror.
Last month, President Goodluck Jonathan's government announced a ceasefire with the terror group but its leader, Abubakar Shekau, denied the deal and the Islamist faction have stepped up their attacks in the country's north.