"Fifteen bodies, 13 girls and two boys, were recovered by local rescue teams and buried in the village," said the official, who supervised the rescue operation.
Divers were working in the Shagari river late on Tuesday searching for more of the children.
The youths were on their way from Dundeji village in Sokoto State to collect firewood in the bush on Tuesday on the other side of Shagari river when their boat sank, Aliyu Abubakar, local administrator of Shagari district, said.
"We woke up to a tragedy yesterday morning, where a boat carrying children capsized mid-river," Abubakar told AFP.
River accidents are frequent in Nigeria, often caused by overloading, poor maintenance, heavy flooding in rainy season and disregard of safety regulations.
In April last year, 29 children from nearby Gidan Magana village in Sokoto drowned in the same river when their vessel capsized while they were also on their way to fetch firewood for their families.
During massive flooding in rainy season in December, at least 76 people drowned when their boat went down in a swollen river in southeast Anambra State.
In one of the country's worst river disasters in May 2021, only 20 people were rescued and more than 150 went missing when a boat transporting people to market broke apart while travelling between Kebbi and Niger states.
Nigeria's waterways authority has tried to ban night-time sailing on rivers to stop accidents, and overloading vessels is a criminal offence, but skippers and crews often flout the rules.
River transport and market trade are common in Nigeria, where roads are often poor. The Niger, West Africa's main river travelling through Guinea to Nigeria's Niger Delta, is a key local trade route.