More than 60 women and girls are reported to have escaped from the Nigerian Islamist group Boko Haram, security sources say.
They were among 68 abducted last month near the town of Damboa in north-eastern Borno state.
Reports say the women escaped when the militants went to attack a military base near Damboa on Friday.
The Nigerian military said it killed more than 50 rebels in a clash that night.
Boko Haram is still holding more than 200 schoolgirls abducted in April.
Local vigilante Abbas Gava told journalists he had "received an alert from my colleagues... that about 63 of the abducted women and girls had made it back home".
"They took the bold step when their abductors moved out to carry out an operation," he said.
A high-level security source in the state capital Maiduguri confirmed the escape, AFP news agency reported.
The BBC's Nigeria correspondent Will Ross says the insecurity is so rife in Borno state and the access so poor that it is not yet clear exactly how many of the young women managed to escape from Boko Haram.
Relatives of three of the women told the BBC they were safe.
Boko Haram triggered an international outcry when it captured 200 girls in Borno's Chibok town on 14 April.
It is demanding the release of its fighters and their relatives in exchange for the girls but the government has rejected this.
Last week three women were arrested for recruiting female members for the militant group, the country's military said.
They were said to have targeted widows and young girls, promising them marriage to Boko Haram members.
A state of emergency is in force in northern Nigeria because of the group's increasingly violent campaign to overthrow the government and create an Islamic state.
Maiduguri was the headquarters of Boko Haram until it was forced out by the military and vigilante groups.
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