Two girls, who were among at least 25 children and a teacher kidnapped from their boarding school in north-western Nigeria's Kebbi state on Monday, have managed to escape, a local official told the BBC.

The pair ran away as their armed captors were leading them into the bushes and got away across farmland, Hussaini Aliyu of Danko Wasagu council said. 

He added that the girls were "back and are safe", but one of them needed medical treatment as she had hurt her leg while fleeing.

The assault left two members of staff dead - a teacher was killed while trying to protect girls and a security guard later died in hospital from gunshot wounds.

A team of soldiers, police and volunteers are combing forested areas in an attempt to rescue the captives seized by the gunmen.

"You must continue day and night fighting. We must find these children," Maj Gen Waidi Shaibu, Nigeria's army chief of staff, told troops sent to Kebbi state.

Over the past decade, schools in northern Nigeria have become frequent targets for armed groups, who often carry out abductions to seek ransom payments or leverage deals with the government.

Police say the gunmen, described locally as "bandits", invaded the Government Girls Comprehensive Secondary School in Maga town at about 04:00 (03:00 GMT) on Monday.

Parents face an agonising wait. 

One inconsolable father, whose daughter is still being held captive, told BBC Hausa that his family had been crying non-stop and "it's hard to go back home and look at their faces".

He said he had two daughters enrolled at the school one of whom had successfully hid from the attackers, but the other had not been so lucky.

"My two daughters hid in the toilet when the armed men invaded their hostel.

"When the [gunmen] ordered all those hiding to come out, or else they'll kill them, one of my daughters got scared and came out," the father said.

He added that he had heard of the abductions after the Muslim early-morning prayer on Monday, and had rushed to the school and been there ever since.

"My daughter is a very bright and easy-going person," he said.

Police say the attackers "engaged police personnel on duty in a gun duel" before climbing over the perimeter fence and taking the girls from their hostel.

The security guard who died had a granddaughter and great-granddaughter at the same school and they are among those kidnapped.

It has devastated his family.

"I found him in his pool of blood," the security guard's daughter told the BBC. "Then they took my daughter and also my granddaughter."

She said she had been unable to eat or sleep ever since.

The attack highlights the persistent security crisis plaguing the region, leaving families in a state of fear. 

Nigeria's central government says it is "deeply concerned" by the abductions. 

In a statement on Monday, Information Minister Mohammed Idris Malagi said the authorities "share in the pain" of the affected families and were working urgently to rescue the girls.

He added that President Bola Tinubu remained "unwavering in his commitment to protect every Nigerian, especially schoolchildren".