ABUJA, Nigeria (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.

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 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.