The fire began with an explosion[14] at around 10:30 a.m. local time[1] (01:30 UTC) when the perpetrator walked into Studio 1 and lit the building on fire with 40 litres (8.8 imp gal; 11 US gal) of gasoline. The gasoline was carried on a trolley after being transferred from two 20-litre cans near the building. He is reported to have been shouting "Die!" (死ね) as he carried out the attack. The perpetrator also poured gasoline over some people, causing them to run out into the street in flames.[15]

As the fire grew by the entrance, people were trapped inside the building. Nineteen dead bodies were found on the third floor by the stairs to the roof attempting to escape.[2] The perpetrator fled the scene but was chased by a Kyoto Animation employee and soon collapsed on the street, where he was apprehended by the police.[7] Multiple unused knives were found lying by the scene.