* Hall of residence attacked by gunmen
* Northern Nigeria home to Islamist sect
* Police investigate political feud as possible motive
LAGOS, Oct 2 (Reuters) - Gunmen opened fire in a student residence in northeastern Nigeria on Tuesday, killing and wounding an unknown number of people, emergency services and a security source said.
The attack took place at the Federal Polytechnic Mubi in Adamawa state which, like much of the north, has been targeted by Islamist insurgents. But police were also looking at whether the killings might have been part of a political feud inside the college.
"Definitely there are casualties but we don't yet know how many dead or injured," said National Emergency Management Agency spokesman 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.
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. (Reporting by Tim Cocks; Additional reporting by Mike Oboh in Abuja; Editing by Robin Pomeroy)