A suicide bomber dressed as a student killed at least 48 people and injured 79 others at a school assembly in northeastern Nigeria on Monday, a hospital official said.

The blast took place at a boys’ science and technical school in Potiskum, Yobe state. Eyewitnesses said the bomber dressed as a student for the attack.

No one has yet claimed responsibility for the attack. But suspicion immediately fell on Boko Haram, the feared armed group responsible for a brutal wave of violence in the country, most of it directed against civilians. Members of Boko Haram have targeted educational establishments before, abducting and killing hundreds of students.

With a name that loosely translates to “Western education in forbidden,” the group is seeking to carve out a separate state in Nigeria’s north to be governed in accordance to its own extreme interpretation of sharia law.

The latest attack appears to have been designed to maximize casualties. Some 2,000 students had gathered for Monday morning's weekly assembly at the Government Comprehensive Senior Science Secondary School when the explosion blasted through the school hall, according to survivors.

"We were waiting for the principal to address us, around 7:30 a.m., 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, where he was being treated for head wounds.

"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 told Reuters.

"A teacher who survived the blast with a 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 morgue attendant said the bodies of the dead at his hospital all appeared to be between the ages of 11 and 20 years old. He spoke on condition of anonymity because he is not authorized to give information to reporters.

Mariam Ibrahim, a teacher at the Government Science Secondary School in Potiskum told Reuters the bomb went off as she was arriving Monday morning.

Potiskum resident Aliyu Abubakar said he heard the explosion when he was dropping off his two sons at a nearby Islamic college. "One of my sons fell down, I came out, dragged him in, and we drove off back home," he said.

A second teacher, asking to remain anonymous, said, "There are some (others) that are critically injured and I am sure the death toll will rise."

Boko Haram has intensified its attacks in the past few weeks since a purported ceasefire agreement, announced by the Nigerian government, was later rejected by the group's leader in a video.

Wire services