14 more children were injured, five of whom are in critical condition, the statement said.
The school is in the city of Maradi, 600 kilometers (370 mi) east of the capital, Niamey.
“At the moment we cannot tell about the origin of the fire,” said Maman Hadi, the regional director of education.
He said classes have been suspended and three days of mourning has been declared in Maradi.
This is the second time this year that students in the West African country have died after a fire broke out in their classrooms. Twenty preschool children were murdered in Niamey in April.
The Council of Ministers on Monday said that preschool classes should not be held in straw-roofed huts after two incidents.
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