Many students are feared dead after suspected Islamist gunmen struck a college in north-eastern Nigeria.
The students were shot dead as they slept in their dormitory at the College of Agriculture in Yobe state.
North-eastern Nigeria is under a state of emergency amid an Islamic insurgency by the Boko Haram group.
Boko Haram is fighting to overthrow Nigeria’s government to create an Islamist state, and has launched a number of attacks on schools.
The number of casualties in the latest attack is unclear but there are fears the death toll could be high.
One hospital source told Reuters news agency that 26 people had been killed.
College provost Molima Idi Mato told Associated Press it could be as many as 50, adding that security forces were still recovering the bodies and that about 1,000 students had fled the campus.
A military spokesman in Yobe state, Lazarus Eli, told Agence France-Presse the gunmen had also set fire to classrooms.
The college is in the rural Gujba district.
In June, Boko Haram carried out two attacks on schools in the region.
At least nine children were killed in a school on the outskirts of Maiduguri, while 13 students and teachers were killed in a school in Damaturu.
In July in the town of Mamudo, Islamist militants attacked dormitories with guns and explosives, killing at least 42 people, mostly students.
Boko Haram regards schools as a symbol of Western culture.
President Goodluck Jonathan ordered an operation in May against Boko Haram.
Many of the Islamist militants left their bases in the north-east and violence initially fell, but revenge attacks quickly followed.
Boko Haram is led by Abubakar Shekau. The Nigerian military said in August that it might have killed him in a shoot-out.
However, a video released last week purportedly showed him alive.
Other previous reports of his death later proved to be unfounded.