KANO, Nigeria - At least 13 people were killed on Monday after an explosion ripped through a school in northeast Nigeria, as students gathered for morning assembly before classes began.
A teacher at the school, a medic and a rescue worker said that blast happened at the Government Comprehensive Senior Science Secondary School in Potiskum, Yobe state.
The rescue worker told AFP that 13 bodies had been taken to hospital with more than 30 others left "with various degrees of injuries". There was no official death toll.
"The students had gathered for the morning assembly when something exploded in their midst with a thunderous sound at exactly 7:50 am (0650 GMT)," added a teacher, who asked not to be identified.
"The explosion has affected many students but I can't say how many because we are now evacuating the victims to the hospital which is just 100 metres away," the teacher added, sobbing.
A medic at the Potiskum General Hospital, where the victims were taken, said scores of students had been admitted.
"We are still receiving casualties from the school which is a stone's throw from here," the medic said.
"Our priority now is to save the injured, so we have not started a headcount of the victims." A local resident, Adamu Alkassim, said there was confusion in and around the school. The scene was a mass of abandoned footwear and blood.
Boko Haram suspected
There was no immediate claim of responsibility for the attack, but Boko Haram militants are likely to be the prime suspects.
The group, which wants to create a hardline Islamic state in northern Nigerian, has previously carried out deadly attacks on schools teaching a so-called Western curriculum since 2009.
In February, gunmen killed at least 40 students after throwing explosives into the dormitory of a government boarding school in Buni Yadi, also in Yobe state.
In July last year 42 students were killed when Boko Haram attacked dormitories in a gun and bomb attack on a government boarding school in the village of Mamudo, near Potiskum.
Boko Haram's most high-profile attack on a school came in April, when fighters kidnapped 276 girls from the town of Chibok in Borno state, also in northeast Nigeria.
More than six months later, 219 of the girls are still being held.
Potiskum, the commercial hub of Yobe state, has been repeatedly targeted by deadly attacks blamed on Boko Haram.
Just last week, at least 15 people were killed in a suicide bomb attack targeting a Shia religious ceremony in the city.
Yobe is one of three northeastern states that has been under a state of emergency since May last year to try to quell the bloody insurgency.
But violence has continued unabated and Boko Haram has seized at least two dozen towns and villages in recent months, raising doubts about the government's ability to control the region.