Katsina, Nigeria-More than 300 Nigerian schoolboys seized in a mass abduction claimed by Boko Haram experienced their first full day of freedom on Friday after a six-day ordeal.

But relief at their survival mingled with concern that many others could still be captive, and the circumstances of their release remained unclear.

Looking dirty, worn-out and distraught, and most of them without shoes, the boys were brought to the governor’s office in Katsina, the capital of Katsina state in northwestern Nigeria, after being released late Thursday.

The assault last Friday on a rural school in Kankara, was initially blamed on criminal gangs who have terrorised the region for years.

But on Tuesday Boko Haram, the brutal jihadist group behind the abduction of 276 schoolgirls in Chibok in 2014, claimed responsibility for the raid. Local officials announced late Thursday that the boys had been released and would spend the night in the protection of security agents. 

A security source, speaking on condition of anonymity, said they had been left in the forest after negotiations between the authorities and the abductors, but gave no further details.

State governor Aminu Bello Masari said “344 are now with the security agencies” and were being taken to Katsina. They would be given medical care before reunited with their families, he said.

“This is a huge relief to the entire country & international community,” President Muhammadu Buhari said on Twitter.

It remained unclear, however, if all the abducted schoolboys had been released, amid ongoing uncertainty over the number taken in the first place.

In an interview with state channel NTA, the governor added: “I think we have recovered most of the boys, it’s not all of them.”

In a video released by Boko Haram Thursday, a distressed teenager said he was among 520 students kidnapped.

The security source said late Thursday that the exact number would only be known after a head count in Katsina.

Alliance of ‘bandits and terrorists’ 

Sources had previously told AFP that the raid was carried out by a well known criminal in the region, Awwalun Daudawa, in collaboration with Idi Minorti and Dankarami, two other crime chiefs with strong local followings, acting on behalf of Boko Haram.

Experts recently warned that jihadists -- operating in the northeast of the country, hundreds of kilometres (miles) from where Friday’s attack occurred -- were attempting to forge an alliance with criminal gangs in the northwest.

President Buhari’s official spokesman Garba Shehu said on Twitter “the northwest now presents a challenge which his administration is determined to deal with.”

“It is unfortunate that the bandits and terrorists continue to get weapons even under the circumstances of the border closure. We are going to dare them.”

Many parents of the missing students in Kankara said they had long feared an attack, given escalating violence in the region.

“Our children told us armed men would come up to the school fence but they never breached the fence... until last Friday,” Hauwa’u Isah, mother of an abducted child said. 

Around 8,000 people have been killed in the northwest since 2011, according to the International Crisis Group (ICG) think tank.

#BringBackOurBoys started trending on social media earlier this week, in reference to a similar hashtag after the Chibok kidnappings.

Small protests to push for the boys’ release took place in Katsina on Thursday as Buhari was visiting the state.

                  “Why we are here today is because we want to tell the federal government that what they are doing is not enough,” protester Jamilu Aliyu Turanci said. “Mr President has failed us.”