Pre-planned operation
Al Jazeera's James Bays reporting from Iraq said that the kidnapping was a pre-planned operation.
"It seems to be a planned operation because the kidnappers had a trailer, on which they loaded the male students and they also had an accompanying car which had gunmen in it."
"The gunmen also fired shots at a police check-post nearby," Bays said.
The students were travelling in two buses. But the bus carrying female students managed to escape and male students in the other bus were taken hostage.
Mosul police told Al Jazeera that they believed the kidnapping was a result of mistaken identity.
They said the kidnappers probably thought the male students to be policemen or police recruits.
However, when they were able to establish their identities as students, they let them go.