“They are young men,” he said, speaking of the kidnappers. “And most of these ladies will be turned into their sex slaves and cooks.”

Ten of the girls escaped as they “were forced to cook for the Boko Haram,” the governor said. “They were told to use the leaves of the trees to clean the plates. That is the opportunity they took to escape.”

Another four jumped from trucks, and all 14 were “so traumatized,” he said.

They were resting in Chibok, where the school is in a forested area known to be a Boko Haram hide-out. The group has targeted students in the past, killing young men and kidnapping young women. It has sometimes let the women go, but there was no indication it would this time. The Nigerian military said on Wednesday that only eight of the girls were still missing, but that was quickly contradicted by the school’s principal, Asabe Kwambura, who said in a phone interview that it was not true.

The military has become notorious for exaggerating its successes against Boko Haram.

The gunmen arrived at the school on Tuesday under the cover of early morning darkness in 60 vehicles, including 40 motorcycles, a mode of transportation favored by Boko Haram, Mr. Shettima said. The students had been staying overnight at the school to take their final exams. The gunmen first attacked the village, setting buildings on fire, then shot and killed a soldier and a police officer guarding the school.

Some reports quoting the principal suggested that the gunmen were wearing army uniforms to fool the administrators and the students. But Mr. Shettima said he could not confirm that, though he noted that members of Boko Haram often dressed in stolen uniforms. The schools in Borno State have been closed after earlier Boko Haram attacks, and most students taking final exams were summoned to Maiduguri, or the southern town of Biu, for safety reasons. But Mr. Shettima said that in the case of the Chibok school, which is in a predominantly Christian area, “there was an assurance from the local people that they would do whatever it takes to protect the community.”