According to Janeth Magomi, the Shinyanga regional police commander, the accident destroyed the dormitory in the Shinyanga municipality, Xinhua reported.
The fire started at about 11 p.m. local time on Wednesday (20.00 GMT), when the girls were already sleeping, the police official added.
The age of the dead and injured was not specified.
"The dormitory was gutted at around 11 p.m. local time when the girls were asleep," said Magomi.
In 2020, 11 pupils were killed and seven others injured in a fire at a primary school dormitory in Tanzania's northwest region of Kagera.