The 79 students and three others were seized early on Monday morning in the region's capital, Bamenda.
The school's principal, the driver, and a teacher are still in captivity, the BBC's Mayeni Jones reports.
The government and separatists in the English-speaking region have been accusing each other of being behind the kidnapping.
A video purportedly showing some of the kidnapped schoolchildren has been shared online, sparking outrage.
An Anglophone separatist movement has been operating in the North-West and South-West regions over the past year.
