The 38 now released people were kidnapped at Government Science College Kagara in Nigeria two weeks ago, reports the news agency AP.
Initially, "hundreds abducted" were reported.
The number was then written down to 42, but was in fact 38 according to local authorities.
A boy was killed in connection with the kidnapping.
"Exposed to horrific torture"
The people were received by the authorities in the city of Minna on Saturday.
"They have been subjected to horrific torture," said State Governor Abubakar Sani Bello, adding:
- They are currently undergoing an in-depth health examination and hopefully they can soon be reunited with their families.
One of the kidnappers was hospitalized after suffering from fatigue.
317 kidnapped in Zamfara
A day earlier, on Friday, 317 girls from several different boarding schools in the state of Zamfara were abducted.
The perpetrators simultaneously attacked a military installation, thus preventing the military from preventing the kidnappings.
There are several armed groups in Zamfara that are known for kidnappings.
The groups often demand ransoms or use the kidnappings for extortion purposes to try to get prison inmates out.