Boko Haram was suspected of killing about 50 students in a suicide attack in northeastern Nigeria on Monday in one of the worst attacks against schools that teach called Western curriculum.
The explosion at a school for boys in Potiskum as students gathered at morning assembly before classes began, causing panic and chaos.
The slaughter came just a day after the release of a new video in which Boko Haram Islamist group leader, Abubakar Shekau, again rejected the Nigerian government's claims of a ceasefire and peace talks.
Students in Integrated Science Government Higher Secondary School were waiting to hear daily direction of the principal when the explosion occurred at 7:50 a.m. (0650 GMT).
Several witnesses described the explosion as "thunderous" and the bloody aftermath of a scene of abandoned shoes, school books, bags and body parts.
"There was an explosion detonated by a suicide bomber. We have 47 dead and 79 wounded," said national police spokesman Emmanuel Ojukwu, adding that Boko Haram is believed to be responsible.
One of the rescue workers said the wounded had "varying degrees of injuries," while the survivors complained of hearing the deafening explosion.
The school has over 1,000 students and is suitable for children age 15 to 20. The victims are all thought their teens.
Uniforms bloodstained
Abdullahi Adamu student said they are in the center of the explosion near the principal's office were thrown in all directions and others were removed from their feet.
"I found myself under the weight of another student, who fell on me. I'm sure he was dead. I was groggy and disoriented for a moment," he told AFP.
"When I realized what had happened, I managed to push the body over me and started running like everyone else. It was confusion everywhere. Everyone was hysterical.
"I saw many people on the ground. The human flesh and blood was splattered all over the place ... I ran out of the school and went home." When my father saw me, I was terrified. I did not realize that my white school uniform was stained with blood and pieces of human flesh. "
The dead and injured were taken to the General Hospital of Potiskum just 100 meters (yards) away. Boko Haram, which wants to create an Islamic state hardliners in northern Nigeria, has carried out deadly attacks previously in schools teaching a plan called Western studies since 2009.
In February, gunmen killed at least 40 students after throwing explosives at a boarding school dormitory government Buni Yadi, also in Yobe state.
In July last year, 42 students were killed when Boko Haram stormed the dormitories in an attack with firearms and bomb in a government boarding school in the town of Mamudo near Potiskum. More high-profile attacks of Boko Haram in a school came in April, when fighters abducted 276 girls Chibok city in Borno State in northeastern Nigeria too.
More than six months later, 219 of the girls are still being held. Monday's attack will raise concerns about the level of security in schools in northern Nigeria. Abdullahi said the settlement was "not fenced properly."
"Anyone can come and go unhindered," he added.
relentless violence
Potiskum, the commercial center of Yobe state, has been targeted repeatedly by deadly attacks blamed on Boko Haram. On Monday, at least 15 people were killed in a suicide bombing at a Shiite religious ceremony in the city.
On Wednesday, 16 men arrested by the military on suspicion of links with Boko Haram were found dead with gunshot wounds a few hours later. Yobe is one of the three northeastern states has been under a state of emergency since last May to try to quell the bloody insurgency year.
But violence continues unabated, Boko Haram has taken over at least two dozen cities and towns in recent months, raising doubts about the government's ability to control the region.
Boko Haram fighters were seen in a new video obtained by AFP on Sunday paraded a tank in an unnamed city that seemingly controlled and Shekau preaching to the locals.
The message in the video for 44 minutes seemed destined to reinforce the claim Shekau has created a caliphate in Nigeria. Shekau, who has previously expressed its solidarity with other jihadist groups and leaders, seemed associated territory under its control with a wider global caliphate.
But he does not submit to the authority of any other leader.