The kidnapping for ransom is the latest in a series of such incidents in northern Nigeria, with a sharp rise in abductions since late 2020 as the government struggles to maintain law and order amid a flagging economy.
The two girls and a boy were found dead, two with gunshot wounds in their legs, said Mustapha Yusuf, principal of the federal government college in the remote town of Birnin Yauri in northwest Nigeria's Kebbi state.
Nine abductees escaped or had been rescued but the kidnappers held the rest, with security forces wary of staging a rescue attempt for fear of harming the children, Yusuf said.
The kidnappers "have been taking cover under the students ... They are in the bush," he said, adding that bandits had used students' phones to call parents and demand a 60 million naira ($146,341) ransom.