Boko Haram militants have seized the north-eastern Nigerian town of Chibok, from where they kidnapped more than 200 schoolgirls in April.
Militants attacked and took control of the town, in Borno state, on Thursday evening, residents who escaped told the BBC.
Boko Haram has repeatedly targeted villages around Chibok over recent months.
The group says it is fighting to create an Islamic state in Nigeria.
The schoolgirl kidnappings in Chibok caused worldwide outrage and sparked a social media campaign.
A senator for Borno state, Ali Ndume, told the BBC Hausa service that security forces posted in Chibok, a relatively small, mainly Christian town, ran away when the insurgents attacked.
Residents told the Sahara Reporters news website that the militants headed to the centre of Chibok and declared that they were taking it over as part of their caliphate.
Musa Ali, a vigilante who tried to defend Chibok, said the militants had attacked in two groups.
“You couldn’t count them because there were so many,” he said.
“All the security and the soldiers, they ran away and left us on our own. They didn’t shoot at them, they just ran. All the ammunition we had was finished, so there was no way we could attempt to hold the area.”
Since the kidnapping of the girls, people have complained that the area was not well protected and many residents of Chibok had already moved to safer parts of the country, fearing another attack.