They crept up to the school under cover of darkness, armed with petrol and automatic weapons.
Most of the teachers and pupils had fled, but some students, one teacher and headmaster Adanu Haruna were still in the compound, one of many rural boarding schools in Nigeria surrounded by forest and farmland.
"They made the students line up and strip naked, then they made the ones with pubic hair lie face down on the ground," Haruna said- eyes wide with horror at describing the attack on the iron-roofed school built by the British, during the colonial rule in the 1950s.
"They shot them point blank then set the bodies on fire."
The Mamudo government school, charred and smelling of scorched blood after 22 students and a teacher were killed there in the July 6 attack near Potiskum in Nigeria's north-east, was the fourth to be targeted by suspected Boko Haram militants in less than a month.
The attacks reveal much about the rebels who are fighting to revive a medieval Islamic caliphate in northern Nigeria, the type of state they are seeking to establish and the impact of their efforts to do so on the African economic powerhouse.
These people are so heartless! And, I really wonder what they truly want...