Eyewitnesses said some of the victims were burned alive in the attack, in Mamudo town, Yobe state.
Dozens of schools have been burned in attacks by Islamists since 2010.
Yobe is one of three states where President Goodluck Jonathan declared a state of emergency in May, sending thousands of troops to the area.
A reporter from the Associated Press found chaotic scenes at the hospital in nearby Potiskum, where traumatised parents struggled to identify their children among the charred bodies and gunshot victims.
Survivors said suspected militants arrived with containers full of fuel and set fire to the school.
Some pupils were burned alive, others were shot as they tried to flee.
The BBC's Will Ross, in Lagos, says this area has frequently been attacked by the Boko Haram militant group.
More than 600 people were believed to have been killed in 2012 by the group, which is fighting to overthrow the government and create an Islamic state in Nigeria's predominantly Muslim north.
Headlines Newsview all
After spending a day with inmates of the Ikoyi and Kirikiri prisons, Lagos, KUNLE FALAYI brings an account of what it is like to be ... Full story
The Vatican on Friday announced the death of Jozef Wesolowski, an ex-diplomat who was to be the first high-ranking Vatican official to stand trial for ... Full story
Rate this article
- Mother And Daughter "Strip" And Sleep With Sugar DaddiesTo Raise £56,000 For Plastic Surgery
- Sacked Employee Shoots Former Colleagues On Live TV - Video
- Man proposes to his boyfriend in church that prohibits gay marriage and gets a standing ovation from the congregation
A stunning and pregnant Mercy Johnson celebrated her birthday with her husband and kids . She looks amazing! ... Full story
Cristiano Ronaldo has given his old friend and former football teammate, Albert Fantrau a special recognition publicly after recounting how he sacrificed his own football ... Full story
When all the butterflies have fluttered away and your wedding day becomes a distant memory, you will discover that you’ve married someone who is just ...
Mr James Adedapo, a retired civil servant has got a nod for his divorce suit against his wife, Oluwatoyin, at the Grade ‘C’ Customary Court ...
Nollywood actress, Rukky Sanda, known for her regular flaunting of her wears on social media, has disclosed that she is not happy that she is ...
Nollywood actress, Mercy Aigbe, is not just making a mark in acting alone but in fashion, hair and recently cosmetic line which she just added. In ...
The Nigerian entertainment industry both Nollywood and acting is really buzzing these days as new talents are being discovered all trying to make a name ...
Nollywood actress, Liz Anjorin, is one blunt actress who does not care what people will have to say about her as she believes she plans ...
Royal Arts Academy in conjunction with Nollywood Workshop released a new block buster movie, titled ‘Code of Silence, ’which explores the very important themes of ...