At least 24 students and teachers have died in a fire at a religious school in Malaysia's capital, Kuala Lumpur, reported BBC.

According to the BBC report, the fire at the Tahfiz Darul Quran Ittifaqiyah broke out in the early hours of Thursday morning. Initial counts put the death toll at 25, but police later revised that down by one. They said the dead were 22 students - all boys between the age of 13 and 17 - and two staff members.

The victims are thought to been trapped in their dormitory as the windows were barred with metal grills. Images and videos circulating online showed the entire upper room of the school ablaze.

"It is one of the country's worst fire disasters in the past 20 years," Khirudin Drahman, director of the fire and rescue department, told AFP.

The blaze was reported at around 5:40 local time on Thursday morning. According to the police it began in the sleeping quarters.

In Islamic tahfiz schools - where children study the Koran - students often live at the school.

"The building was surrounded by metal grills that could not be opened from the inside. The students, after realising the fire and heavy smoke, tried to escape through the window," Fire and Rescue Department operations deputy director Soiman Jahid told reporters outside the school, "Because of the grills though, they could not escape."

Meanwhile, the police were still investigating what caused the fire but that it likely was caused by short circuit or a lit mosquito repellent coil.

A neighbour living next door to the school told the Reuters news agency they heard screams and saw the flames.

"The children were crying for help, but I couldn't help them as the door was already on fire," he said.

Kuala Lumpur Police chief Amar Singh said the bodies were "totally burned".

Officials said fire engines were at the site within minutes, and the blaze was put out within an hour.

A number of students were also taken to hospital, some suffering from smoke inhalation.

According to local media reports, there have been more than 200 fires at such schools since 2015.