The blaze in Nyeri county's Hillside Endarasha Academy broke out at around midnight, police said, engulfing rooms where the children were sleeping.
The primary school caters to some 800 pupils, aged between roughly five and 12.
"There are 17 fatalities from this incident and there are also others who were taken to hospital with serious injuries," national police spokesperson Resila Onyango told AFP.
"The bodies recovered at the scene were burnt beyond recognition," she said.
Police said the average age of the victims was around nine years old.
"More bodies are likely to be recovered once (the) scene is fully processed," she said.
The cause of the fire remains unknown, she said, but an investigation had been launched.
President William Ruto expressed his condolences for those killed.
"Our thoughts are with the families of the children who have lost their lives in the fire tragedy," he said in a post on X.
"This is devastating news."
He said he had instructed officials to "thoroughly investigate this horrific incident", and promised that those responsible will be "held to account".
The school is located around 170 kilometres (100 miles) north of the capital Nairobi, in Nyeri county.
The Kenyan Red Cross said it was on the ground assisting a multi-agency response team.
In a post on X, it said it was "providing psychosocial support services to the pupils, teachers and affected families".The inferno occurred late Thursday at the Hillside Endarasha Academy in Kieni, in the country’s Nyeri county, Resila Onyango, a spokesperson for the Kenya National Police Service said. She added their bodies had been “burnt beyond recognition.”
“The cause of fire is unknown at this time but we will update the public when we know more,” Onyango told CNN.
Government spokesperson Isaac Mwaura said in a statement Friday that the fire broke out at around midnight in the male dormitory of the mixed private boarding school, adding that more than 150 boys were in the dormitory at the time.
Kenya’s education ministry said 824 students – 402 boys and 422 girls – were enrolled in the school. It added that 156 of the boys and around 160 girls were boarders while the rest were day scholars.
Deputy President Rigathi Gachagua said that 70 children are still unaccounted for.
“We still have 70 kids that are unaccounted – that does not mean they are perished or they are injured. The word is that they are unaccounted for. We are praying and hoping for the best,” he said at a press conference Friday.
Gachagua said that some parents, hearing the news of the fire, came to the school to collect their children without informing school officials.
“I am appealing to each and every parent who took their child from here to report… so that we know where that child is,” he said.
Kenyan President William Ruto on Friday offered his condolences. Describing the incident as “devastating news,” Ruto said “our thoughts are with the families of the children who have lost their lives in the fire tragedy at the Hillside Endarasha Academy in Nyeri County,” in a post on X.
“I instruct relevant authorities to thoroughly investigate this horrific incident. Those responsible will be held to account,” his post continued, adding his government was “mobilizing all the necessary resources to support the affected families.”
Kenya Red Cross personnel and relatives try to comfort a woman reacting near the burned-out dormitory.
Distraught parents converged on the school Friday morning, waiting anxiously for news as authorities searched for bodies and survivors.
The Kenya Red Cross also posted a statement Friday, saying it would provide “psychosocial support services to the pupils, teachers and affected families.”
The statement added that 11 children have so far been taken to hospital, with the area of the fire cordoned off by police.
Kenya Red Cross, alongside a “multi-agency response team,” is currently on the ground responding add has set up a tracing desk at the school, the statement continued.
School fires – often attributed to arson and overcrowding – are relatively common in Kenya, where similar tragedies have led to multiple casualties in the past.
In 2017, at least nine students died when a boarding school in the capital Nairobi erupted in flames. The government said at the time that the fire “was not an accident” but an “arson,” and part of a rising trend of deliberate school fires. From 2015 to 2016 around 350 schools had caught fire, according to official figures reported by Reuters.
Deadly blazes
There have been numerous school fires in Kenya and across East Africa.
In 2016, nine students were killed by a fire at a girls' high school in the Kibera neighbourhood of Nairobi.
In 2001, 67 pupils were killed by an arson attack on their dormitory at the Kyanguli Mixed Secondary School David Mutiso in Kenya's southern Machakos district.
Two pupils were charged with the murder, and the headmaster and deputy of the school were convicted of negligence.
In 1994, 40 school children were burned alive and 47 injured in a fire that ravaged the Shauritanga Secondary School for Girls in the northern region of Kilimanjaro in Tanzania.
