Grieving relatives and former classmates bid a solemn farewell on Thursday to 21 children who died in a boarding school fire in central Kenya earlier this month, laying nine of them to rest in small white coffins.

Dozens of children carrying floral wreaths led funeral processions for the boys from Hillside Endarasha Academy in Nyeri town, who were aged between nine and 13.

They were trapped in their dormitory as the blaze spread through the building on Sept. 6. Kenya has a sad history of school fires. There were more than 60 cases of arson in public secondary schools in 2018, according to the most recently available government data.

Thousands of mourners earlier attended a memorial ceremony for the young victims, whose photographs were displayed on top of coffins, along with flower bouquets.

"These young souls, innocent. Young boys," Deputy President Rigathi Gachagua said at the service. "Our heart cries for them."

It is not yet known what caused the blaze, but researchers say many similar fires have been set by students protesting harsh discipline and poor conditions.

In 2017, ten girls lost their lives in a high-profile fire at a school dormitory in Nairobi. A teenage student was charged with manslaughter for committing arson.

Maryanne Mwangi's 14-year-old daughter, Virlear, was among the victims in 2017. News of the latest fire infuriated Mwangi, who said the government had done nothing to improve conditions in schools during the intervening years.

"I (didn't) want to look at social media because I'm telling myself, 'it can't be happening again,'" she told Reuters.

"I always prayed Bubbles will be the last child who will die of a school fire," Mwangi said, using her daughter's nickname.

Kenyan boarding schools often impose too many strict rules, creating discontent that lead some teenagers to commit arson so they could go home, Mwangi said.

"Our schools are a school of rules. It's actually like a military camp," she said.