The suspected arsonist behind the blaze that killed at least 33 people and left 36 injured, some critically, at an animation studio in Japan yelled “You die!” when he burst inside and doused the building with fuel, officials said.

The 41-year-old man, who has not been named, was injured in the conflagration at the Kyoto Animation Co. studio and was taken to a hospital. He is not a company employee, officials said.

He was later arrested by police, who said he also had a backpack containing several knives and admitted to the crime, though a motive was unclear.

A person who saw the suspect being approached by police told NHK public television that he had burns on his arms and legs — and that he was complaining that something of his had been “stolen,” possibly by the company.

Several witnesses described the harrowing scene.

“There was an explosion, then I heard people shouting, some asking for help,” a woman told TBS TV. “Black smoke was rising from windows on upper floors, then there was a man struggling to crawl out of the window.”

A male witness told NHK that he heard “two loud bangs” that sounded like explosions.

A woman living nearby told the Kyodo news agency she saw at least one injured person outside the building.

“A person with singed hair was lying down and there were bloody footprints,” the 59-year-old told the local news outlet.

Prime Minister Shinzo Abe posted a message on Twitter: “So many people were killed or injured. It’s so appalling I can’t find a word to say.”

“I pray for … their souls,” he added.

Kyoto Animation, better known as KyoAni, was founded in 1981 as an animation and comic book production studio.

The company — whose hits include “Lucky Star,” ”K-On!” and “Haruhi Suzumiya” — does not have a major presence outside Japan, though it was hired to provide animation work on a 1998 “Pokemon” feature that appeared in US theaters and a “Winnie the Pooh” video.

“We are in the process of learning what happened,” said a woman who answered the phone at the firm’s headquarters in the city of Uji. “We cannot tell you anything more.”

Fire officials said more than 70 people were in the building at the time of the blaze — the worst mass killing in Japan since a man stabbed and killed 19 people at an assisted-living facility in western Tokyo in 2016.

There was an outpouring of support for the victims in Japanese-language social media, with some users posting images of animation — many with the hashtag “#PrayForKyoani.”

“I don’t know what I should be thinking now,” tweeted Yutaka Yamamoto, an animation director who once worked at the company. “Why, why, why?”

In Japan, convicted arsonists can face the death penalty.

With Post wires