Sobbing parents sifted through the ashes of the girls dormitory at the Buddo primary school Tuesday, trying in vain to identify their daughters in the charred piles of bones and skulls.
"Help me, oh God please help me," wailed Jacqueline Bakoba as she lifted up part of the collapsed roof looking for her missing daughter, Betty.
By the time the fire brigade reached the school, most of the dormitory had burned down and part of the roof and inner walls had collapsed. The fire burned away almost all the mattresses and children's clothing and the intense heat warped the metal bed frames.
Teacher Frederick Bugmbe said there were 58 girls in the dormitory, but some managed to escape through narrow windows.
Hundreds of parents arrived at the school, which has around 1,000 students, to search for their children. The school is about seven miles from the capital, Kampala.
Police said it appeared 19 students and two adults died in the blaze but they were still searching the site for remains.
Lydia Namusisi, 14, who sleeps in a dormitory next door, said she was woken up by a loud bang. When the girls tumbled out of bed, they found the dormitory already blazing.
Sylvia Nakatte said she received a phone call to tell her that her 12-year-old daughter, Mary, had died.
"I rushed to the school but her body cannot be identified," she said, weeping and clawing at the sodden ashes.
Authorities were investigating the cause of the fire, said police spokeswoman Judith Nabakooba.