"We (staff) and the students ran into the bush for safety", he said.
Residents and civilian militia in Dapchi say they believe the jihadists had planned to kidnap schoolgirls in their town too.
When the Boko Haram fighters got to the school, they found it empty - but they looted it anyway. In April 2014, the group kidnapped more than 270 girls, 100 of whom were released in a prisoner exchange last September.
In a statement signed and sent to DAILY POST by its spokesperson, Emma Powerful, the pro-Biafra group said the refusal to release its members is the worst form of "immorality and conspiracy".
Reacting to the development, the IPOB, in a statement by its Media and Publicity Secretary, Comrade Emma Powerful, noted with dismay the release of another group of Boko Haram suspects "while innocent IPOB family members are still being illegally and unlawfully detained, some for almost three years without trial as in the case of David Nwawuisi at Kuje prison in Abuja". Tens of thousands have died in years of fighting between the group and government forces.
The kidnapping drew the world's attention to the jihadist insurgency in northeast Nigeria.
Jail terms ranged from three to 60 years, said the ministry.
It also said a total of 526 people allegedly affiliated with Boko Haram had been released for rehabilitation during the second stage, and said 73 cases had been adjourned. Some fled to the bush, others into their homes.
The Indigeneous People of Biafra, IPOB, has decried what it described as the worst form of judicial immorality and conspiracy, the continuous release of violent Boko Haram suspects and detention of peaceful IPOB members. A further 468 suspects were discharged and 28 suspects were remanded for trial in Abuja or Minna.