The dormitories of St. Mary`s Catholic Primary and Secondary School after gunmen abducted children and staff in Papiri, Nigeria, on Friday.Christian Association of Nigeria via AP

Fifty of the 303 schoolchildren abducted from a Catholic school in north-central Nigeria`s Niger state have escaped captivity and are now with their families, the school authority said Sunday, bringing relief to some distraught families after one of the largest school abductions in Nigeria`s history.

The schoolchildren, aged between 10 and 18, escaped individually between Friday and Saturday, according to the Most Rev. Bulus Dauwa Yohanna, chairman of the Christian Association of Nigeria in Niger state and the proprietor of the school. A total of 253 schoolchildren and 12 teachers are still held by the kidnappers, he said in a statement.

"We were able to ascertain this when we decided to contact and visit some parents," Yohanna said.

The pupils and students were seized together with their teachers by gunmen who attacked the St. Mary`s School, a Catholic institution in Niger state`s remote Papiri community, on Friday. No group has yet claimed responsibility for the abductions and authorities have said tactical squads have been deployed alongside local hunters to rescue the children.

It was not immediately clear where the Niger state children were being held or how they managed to return home. Nigeria`s military and police did not immediately respond to an Associated Press inquiry.

"As much as we receive the return of these 50 children that escaped with some sigh of relief, I urge you all to continue in your prayers for the rescue and safe return of the remaining victims," the Yohanna said.

The Niger state attack happened four days after 25 schoolchildren were seized in similar circumstances in neighboring Kebbi state`s Maga town, which is 106 miles away.

Both states are in a northern region of Nigeria where dozens of armed gangs have used kidnapping for ransom as one way of dominating remote communities with little government and security presence.

Satellite image shows that the Niger state school compound is attached to an adjoining primary school, with more than 50 classroom and dormitory buildings. It`s located near a major road linking the towns of Yelwa and Mokwa.

School kidnappings have come to define insecurity in Africa`s most populous nation, and armed gangs often see schools as "strategic" targets to draw more attention.

Niger state hurriedly closed down all schools after Friday`s attack, while some federal colleges in conflict hotspots across the region were also closed by the Nigerian government.