Witnesses said a suicide bomber disguised in a school uniform carried out the attack at the Government Comprehensive Senior Science Secondary School in Potiskum, Yobe state.
“So far, the number of the dead is 48, while 79 are injured. I counted the bodies, mostly students and a few teachers,” a nurse at Potiskum General Hospital, just about 100 metres from the school, told Reuters news agency.
“A teacher who survived the blast with minor injury said the bomber dressed like a student and was also on the assembly ground with the students,” she said, asking to remain anonymous.
A teacher, also asking to remain anonymous, said, “There are some [others] that are critically injured and I am sure the death toll will rise.”
About 2,000 students had gathered for Monday morning’s weekly assembly at the school when the explosion blasted through the school hall, according to survivors.
“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 told the Associated Press from the general hospital, where he was being treated for head wounds.
There was no immediate claim of responsibility but the armed group Boko Haram frequently attacks schools in northern Nigeria, where the fighters have control over large areas.
The group, whose name translates roughly as “Western education is sinful” in the local Hausa language, is described by the government as the biggest threat to security in the country, which is Africa’s biggest economy and leading oil producer.
The government is under pressure to take adequate security measures to protect schools, especially after more than 200 female students were abducted earlier this year.
Another suicide bombing in Potiskum killed 30 people one week ago, when suspected Boko Haram fighters attacked a procession of Shia Muslims marking Ashoura.