Two of the three staff members abducted are still being held, according to Fonki Samuel Forba, moderator of Cameroon's
He said the schoolchildren, who were kidnapped on Sunday night from a church school, had been left at a church near Bamenda, the North West Region's capital.
Mr Forba said the students looked tired and appeared to have suffered during their captivity.
He pleaded with the kidnappers to free the staff still being held, and has asked parents and guardians to take their children home.
The spokesman added that the Presbyterian boarding school with 700 students is being closed because of the security situation.
He said: "It is unfortunate we have to close the school and send home 700 children.
"Their security is not assured by the state and armed groups constantly attack and kidnap them."
Mr Forba added that the school had previously had some students kidnapped, a situation which was resolved when the church paid a ransom of 2.5 million francs (about £3,000) to the armed gang.
"We can no longer continue," he said.
Cameroon's north-west and south-west areas are beset by instability caused by English-speaking separatists.
Fighting between the military and separatists increased after the government clamped down on peaceful demonstrations by English-speaking teachers and lawyers protesting what they said was their marginalisation by Cameroon's French-speaking majority.
Hundreds have been killed in the past year and the separatists have vowed to destabilise the regions as part of the strategy for creating a breakaway state, which they say will be called Ambazonia.
They have attacked civilians who do not support their cause, including teachers who were killed for disobeying orders to keep schools closed.
There have been kidnappings at other schools, but the group taken on Sunday was the largest number abducted at one time in Cameroon's Anglophone regions.
The separatists have also set fire to at least 100 schools and driven out students and teachers from buildings taken over as training grounds.
The North West regional governor Deben Tchoffo said this week that the government is providing adequate security for schools.
The governor said: "I must insist that we have taken enough measures to protect schools, but we also need the assistance of all. People should inform the military whenever they see strange faces in their villages."
Tah Pascal, the father of one of the kidnapped students, said he does not trust what the governor has said.
He said: "How can he always talk of protection and security when our schools are torched every day, our children tortured and their teachers killed.
"This is done in spite of the presence of the military."
Some of the parents said they were relocating their children to safer areas.
Stay up to date with the latest news stories from a Christian perspective. Sign up to our daily newsletter and receive more stories like this straight to your inbox every morning.