At least 22 children drowned on their way to school when their boat capsized in swollen waters of the Nile in Sudan on Wednesday.
A woman on board also died when the vessel carrying more than 40 children sank in Bouhayra, about 750 kilometres north of Khartoum from the capital, the SUNA news agency reported.
Rescue workers were sent to recover victims' bodies, the Sudanese civil defence said.
"The accident was caused by engine failure half-way across because of a strong current," SUNA said.
According to witness Ibrahim Hassan, at least nine children survived the boat sinking.
SUNA said the small boat was overloaded, carrying about 30 sacks of sweet potatoes and 10 bags of grain in addition to the children and the woman, who worked at a local hospital.
Villagers in the region rely on wooden boats to cross the Nile.
A witness said the boat had been crossing the river against the current.
"All the families (in the area) are in mourning," said the witness, who did not want to be named.
It is Sudan's deadliest Nile accident since August 2000 where 50 students drowned when their wooden barge overturned about 350 kilometres southeast of Khartoum.
In September 2014, 13 Sudanese drowned when a boat sank north of Khartoum.
The Nile, which is about 6,700 kilometres long, is formed by the convergence of the White Nile, which has its source in Lake Victoria, and the Blue Nile, which originates in Ethiopia's Lake Tana.
The two rivers meet in Khartoum before the Nile crosses through Egypt to reach the Mediterranean.
Water levels in the river rise every year during Ethiopia's rainy season, and United Nations aid agencies regularly warn of floods in Sudan between July and November.
Heavy rains in Khartoum on Wednesday morning flooded the capital's streets and electricity was cut in most neighbourhoods.
Authorities in the capital announced the suspension of classes until the end of Eid Al Adha.