A suspected Boko Haram suicide bomber disguised in school uniform has killed 47 students in northeast Nigeria in one of the worst attacks against schools teaching a so-called Western curriculum.
The explosion on Monday ripped through an all-boys school in Potiskum just as students gathered for morning assembly before classes began, causing panic and chaos.
The massacre, described by President Goodluck Jonathan as a "dastardly attack", came just a day after the release of a new Boko Haram video in which the Islamist group's leader, Abubakar Shekau, again rejected Nigerian government claims of a ceasefire and peace talks.
UN Secretary-General Ban Ki-moon called on Nigerian authorities to bring the perpetrators of the school attack to justice.
The UN chief "is outraged by the frequency and brutality of attacks against educational institutions in the north of the country", his spokesman said.
Students at the Government Comprehensive Senior Science Secondary School were waiting to hear the principal's daily address when the explosion happened at 7.50am local time.
Several witnesses said the blast was "thunderous" and described a bloody aftermath of abandoned footwear, charred school books, bags and body parts.
"There was an explosion detonated by a suicide bomber. We have 47 dead and 79 injured," national police spokesman Emmanuel Ojukwu said, adding that Boko Haram was believed to be responsible.
Ojukwu also confirmed local media reports that the bomber was disguised as a student at the school, which has more than 1000 pupils aged 15 to 20.
Yobe state governor Ibrahim Gaidam ordered the immediate closure of all public schools in the Potiskum area and slammed the government in Abuja for failing to tackle the insurgency.
"Urgent action must be taken right now to restore a fast-waning public confidence by doing whatever it takes to stop the escalating violence," he said in a statement.
Jonathan promised those affected that his government would find the culprits, "no matter how long it takes".
