KANO (AFP) - Nigerian soldiers moved house to house in an urgent bid to hunt down attackers responsible for the massacre of 40 people who were shot or had their throats slit in a student housing area. The raid in the early hours of Tuesday near a polytechnic university shook the town of Mubi, located in Nigeria’s volatile northeast, where extremist group Boko Haram has carried out scores of previous attacks. Nigerian President Goodluck Jonathan called the gruesome off-campus attack “sad and shocking” but its motives remained unclear. Police have given a death toll of 25, saying at least 22 of the victims were students. A school official said that the toll was at least 40, but could not immediately say how many were students.