Lagos: Nigeria's north-eastern Yobe state has ordered the closure of all secondary schools after a massacre in which suspected Islamist extremists killed 42 people in an attack on a boarding school.

Yobe Governor Ibrahim Gaidam directed ''all secondary schools in the state be closed down until … a new academic session begins in September''.

In the attack on Saturday, Boko Haram sect members rounded up students and staff in a dormitory before throwing explosives inside and opening fire.