The towel and shoe racks, as well as the walls on the third floor of the tahfiz school where a fire claimed 23 lives last week, were splashed with petrol.

"The fire spread to the ceiling and consumed the door on the third floor.

"The fire spread quickly due to gas released from two LPG cylinders," Fire and Rescue Department director-general Wan Mohd Nor Ibrahim told a press conference in Putrajaya today.

Based on the findings, investigators have classified the incident as a case of "incendiary fire."

Of those who perished in the pre-dawn blaze at the Darul Quran Ittifaqiyah school in Kuala Lumpur, 21 were students aged between six and 14.

The police have arrested seven teenagers, including an 11-year-old, in connection with the case, which is believed to have been triggered by a misunderstanding.

Police brought one of the suspects to the tahfiz school today.

Bernama reports that the suspect, who had his head covered, was brought to the school's back gate, as well as the dormitory which was on the third floor of the building.

The police and the suspect left the scene of the crime after an hour.

Police earlier did a 3D imaging scan of the school.