Police in Kenya have been ordered to investigate the circumstances that led to a deadly fire at a boarding school, which killed at least 18 pupils with an average age of nine.

Investigators should "assess whether or not the tragedy may have resulted from negligence and/or recklessness", the chief prosecutor said in a statement.

The cause of the fire in the boys' dormitory at Hillside Endarasha Academy is still unknown, and 50 pupils are unaccounted for.

Identification of the bodies is expected to take place on Monday.

Director of Public Prosecutions Renson Ingonga said the tragedy "evokes bad memories of other similar school fire incidents which many times point to negligence" and failure to comply with school safety standards.

"Any person found culpable towards the fire tragedy shall be expediently taken through the due process of criminal trial," he added in a statement on X.

Multiple Kenyan laws and a school safety standards manual set out safety and protection measures with which schools must comply.

Kenya's national gender and equality commission said in a statement that initial reports indicating the dormitory was overcrowded were "deeply concerning".

The fire broke out in the dormitory housing 156 boys in the remote area in Nyeri county around 23:00 local time on Thursday. Firefighters were delayed by bad roads, but people living nearby rushed to rescue the boys.

It "is a catastrophe beyond our imagination", government spokesman Isaac Mwaura said at the school on Saturday. "It is truly devastating for the nation to lose such a number of young and promising Kenyans. Our hearts are heavy."

Around 50 children are unaccounted for - some thought to have escaped into the local community or been picked up by their parents without the school's knowledge.

Mr Mwaura said on Saturday that more than 20 children had now been accounted for, after 70 were initially reported missing on Friday. He urged the media to not "rush to make conclusions about the numbers" as DNA testing would take days.

On Saturday, criminal investigators and government pathologists had sealed off the site for analysis. Identification of the bodies would not take place until Monday at a hospital, another official told journalists.

"Some of the bodies were burnt beyond repair," the official said.

That means parents, desperate for news, could have to wait two more days before knowing the fate of their children.

President William Ruto has declared a three-day national mourning period to start on Monday.

School fires are relatively common in Kenyan boarding schools, where concerns have been raised about safety standards.

In 2022, a dormitory in western Kenya burnt down, with several students later arrested on suspicion of arson.

In 2017, 10 students died in an arson attack at Moi Girls High School in the capital Nairobi.

At least 67 students died in Machakos County, south-east of Nairobi, in the deadliest Kenyan school arson that took place more than 20 years ago.

A report released four years ago warned that many secondary schools in Kenya were not well prepared to respond to fires and didn’t adhere to government safety standards.

The report by the country’s auditor general revealed that many schools lacked proper equipment to handle fire outbreaks and were not constructed in accordance with required safety standards.