Suspected Boko Haram Islamists killed at least 43 people when they opened fire on secondary school students as they slept in a dormitory overnight.
Gunmen stormed the Federal Government College in the town of Buni Yadi in Yobe state according to military sources.
The name Boko Haram means "Western education is forbidden" and school attacks have featured prominently in the group's four-and-half Islamist uprising, which has killed thousands of people.
A military spokesman said the gunmen "opened fire on student hostels" at the college, around 60km from the state capital Damaturu, which includes students aged 11 to 18.
Yobe is one of three northeastern states which was placed under emergency rule in May last year when the military launched a massive operation to crush the Boko Haram uprising.
At least 40 students were killed in September at an agriculture training college in Yobe after Boko Haram gunmen stormed a series of dorms in the middle of the night and sprayed gunfire on sleeping students.
More than 1,000 people have been killed in the northeast since the emergency measures were imposed, despite the enhanced military presence.
Boko Haram, declared a terrorist organisation by Nigeria and the United States, has said it is fighting to create an Islamic state in Nigeria's mainly Muslim north.