A video said to be from the jihadist group Boko Haram shows some of more than 300 Nigerian schoolboys kidnapped last week.
In the video, filmed in a forest, gunmen with their faces covered stand guard over boys, some of whom look no older than 10.
One child is made to issue demands on behalf of the group.
The boys were snatched from a boarding school in the north-western state of Katsina.
The attack was the first of its kind in north-western Nigeria.
Despite the Boko Haram claim that it was behind the abductions, the Nigerian authorities say they were carried out by local gangs connected to the Islamist group.
Boko Haram has been notorious over the last decade for school kidnappings, including in Chibok in 2014, when nearly 300 schoolgirls were seized.
Its name loosely translated as “Western education is forbidden”.
However, these abductions have until now taken place in the north-east, where Boko Haram is based.
What does the video show?
The six-minute footage – which has not been independently verified – features a boy in the foreground whose clothes and face are dishevelled.
Dozens of children, some of them appearing to be very young, stand in the background, pleading.
In a mix of English and Hausa, the main speaker says they were kidnapped by Boko Haram leader Abubakar Shekau’s gang.
He says some of the boys have been killed by Nigerian fighter jets and calls for the closure of schools other than Koranic schools.
He adds that all the government troops who have been sent to help them should be sent back.
At one point his voice appears to break and the other children begin to cry. It’s a distressing watch, BBC Nigeria correspondent Mayeni Jones says.