At least 25 people, including 23 students and two wardens, died in a fire at a religious school in Kuala Lumpur, Malaysia, on Thursday, BBC reported. “I think it is one of the country’s worst fire disasters in the past 20 years,” said Khirudin Drahman, director of the Fire and Rescue Department. “It really does not make sense for so many to die.”

The blaze at the Tahfiz Darul Quran Ittifaqiyah broke out around 5.40 am. Firefighters arrived at the scene and doused the flames in an hour. The cause of the fire is not known yet.

Seven injured students were also taken to hospital and 11 were rescued, Al Jazeera reported. Some also suffered smoke inhalation.

Students at tahfiz schools, where they are taught to memorise the Quran, often live at the premises. Photographs and videos being shared online show the entire upper floor of the school, where the students would have been sleeping, up in flames.

Kuala Lumpur Police Chief Amar Singh said many of the victims were trapped inside the dormitory, which had only one entrance, and probably suffocated. The boys were 13 to 17 years old. An official said they saw bodies piled on top of each other, indicating that there could have been a stampede as the students tried to escape.