Photo/Illutration The Kyoto Animation building burns in Kyoto on July 18. (Asahi Shimbun file photo)

KYOTO--The fate of 36 people killed in an arson attack here was sealed in the first two minutes as smoke and gas engulfed escape routes inside the famed Kyoto Animation Co. studio.

The Fire Disaster Management Agency released a simulation showing how the No. 1 studio building was filled with suffocating fumes within 120 seconds or so.

The data, announced Dec. 23, is part of an analysis of evacuation behavior conducted by the Kyoto City Fire Department.

According to the simulation, a phenomenon known as deflagration, or rapid burning, occurred almost immediately after the perpetrator ignited gasoline he had poured on the first floor.

The spiral staircase area that was set on fire went up in flames and smoke within 10 seconds.

After 30 seconds, stairs between the 2nd and 3rd floors also filled with smoke.

After 1 minute, conditions inside the building would have been critical.

After 1 minute and 30 seconds, some individuals inside jumped from a balcony on the second floor or from windows. Others were able to evacuate by descending a ladder.

Twenty people, the most, died in a stairwell leading from the 3rd floor to a rooftop structure filled with smoke.

After about 2 minutes, the entire building was filled with high-temperature combustion gas and it would have been impossible to escape.

In compiling its evacuation analysis, Kyoto City Fire Department listened to stories from nearly all survivors.

A total of 36 people died in the July 18 attack.

The fire spread rapidly owing to the high open ceiling structure of the spiral staircase, among other factors, officials said.

(This article was written by Satoko Onuki and Koshin Mukai.)