Gunmen opened fire on students in a college in the northeast Nigerian city of Mubi on Tuesday, killing and wounding an unknown number, emergency services said.
A college spokesman said at least 26 students were killed at a student residence.
The attack took place at Federal Polytechnic Mubi in Adamawa state which, like much of the north, been targeted by Islamist insurgents.
"Definitely there are casualties but we don't yet know how many dead or injured," said the spokesman of the National Emergency Management Agency, Yushua Shuaib.
The Boko Haram Islamist sect, which usually targets politicians or security forces, has also attacked students in the past and has cells in Adamawa.
Mr. Shuaib said it was not clear if the attack was carried out by Boko Haram or if it was related to a dispute between rival political groups at the college.
He said police were investigating the possibility the shootings were prompted by a fallout between rival gangs over a student union election on Sunday.
"They think the ones who were disgruntled might have been the ones who were doing the attack," he said.
A security source confirmed that this possibility was being investigated, adding that security forces had raided the residence over the weekend, and arrested some students and seized a number of weapons.