The raid in the early hours of Tuesday near a polytechnic university shook the town of Mubi in Nigeria’s volatile northeast, where Islamist extremist group Boko Haram has carried out scores of previous attacks.
Last week in Mubi, Nigeria’s military conducted a high-profile raid targeting the group, killing a senior Boko Haram figure and arresting 156 suspected members.
President Goodluck Jonathan called the gruesome off-campus attack “sad and shocking” and ordered an investigation, but its motives remained unclear, with some officials suggesting it may have been linked to a recent student election.
“We have made several arrests — in fact we have arrested many suspects in connection with the killing,” said police spokesman Mohammed Ibrahim, declining to give details.
A school official said on condition of anonymity that most of those arrested were students, including those seeking to flee Mubi.
Nigerian soldiers moved house to house Wednesday in an urgent bid to hunt down the attackers.
Police have given an official death toll of 25, saying at least 22 victims were students. The school official said that the death toll was at least 40, but he could not immediately say how many were students.
“Based on accounts from locals, at least 40 people were killed in the attack,” the official from the polytechnic school said on condition of anonymity because he was not authorised to speak publicly.
Ibrahim said security forces had blanketed Mubi, a commercial hub and university town located near the border with Cameroon in Nigeria’s Adamawa state.
According to Ibrahim, the attackers knew their victims and called them out by name in a student housing area off-campus of Federal Polytechnic Mubi, an ethnically mixed school with several thousand students.
Victims were shot or had their throats slit, he said.
Residents said it seemed the victims were both Muslims and Christians, but police had not commented as is often the case in Nigeria, where ethnic and religious divisions regularly lead to unrest.
The town had already been under a 3:00 pm to 6:00 am curfew in the wake of last week’s raid, and it remained in place on Wednesday.
The suggestion that the killings were linked to the student election raised questions over how and why the dispute would have turned so violent.
There were suggestions of ethnic tensions between the mainly Muslim Hausas and predominately Christian Igbos involved in the vote, and a spokesman for the National Emergency Management Agency said some of the victims were candidates.
At the same time, Boko Haram has continually widened its targets and its attacks have become increasingly sophisticated.
A rights activist and expert on religious violence in northern Nigeria, Shehu Sani, said investigators should first concentrate on the role potentially played by the Islamist insurgents.
“There is no student rivalry in the history of Nigeria that has ever led to this kind of massacre,” said Sani.
Nigerian officials have been seeking to show success in the fight against Boko Haram with a number of raids and arrests. There had been a lull in major attacks in recent weeks.
The Islamist extremists have been blamed for more than 1,400 deaths since 2010 as part of their insurgency in northern and central Nigeria, Africa’s most populous nation and largest oil producer, divided between a mainly Muslim north and predominately Christian south.
Maxwell Dukku, a spokesman for Adamawa’s deputy state governor, said the state’s political leaders “really don’t know why this has happened.”
Boko Haram has claimed to be seeking an Islamic state in northern Nigeria, but its demands have repeatedly shifted and it is believed to include a number of factions with varying aims.
Imitators and criminal gangs are also believed to have carried out violence under the guise of the group.