At least 33 people have been killed after a man screamed “You die!” and burst into a Japanese animation production studio.
The blaze at the three-storey Kyoto Animation studio in Japan’s ancient capital on Thursday morning left another 36 people injured, some of them critically.
Local media quoted police as saying the man broke into the premises and sprayed an unidentified liquid around the studio.
The 41-year-old suspect has been detained and was taken to hospital with injuries. Police are investigating him on suspicion of arson.
He was not a company employee.
Japan’s Prime Minister Shinzo Abe described the incident as "too appalling for words".
Twenty of the people who died did so on the third floor of the building and some on the stairs to the roof, which apparently collapsed.
Two more people were found dead on the first floor, 11 others on the second floor.
Survivors who saw the attacker said he was not a colleague and that he was screaming “You die!” when he dumped the liquid and started the fire at around 10.30am local time (1.30am GMT), according to Japanese media reports.
Footage on Japan’s NHK national television showed grey smoke billowing from the charred building. Other footage showed windows blown off.
“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.”
Witnesses in the neighbourhood said they heard bangs coming from the building, and others said they saw people coming out blackened, bleeding and walking barefoot, Kyodo News reported.
Police also found knives at the scene, reported local media, though it was unclear if they belonged to the attacker.
Rescue officials set up an orange tent outside the studio building to provide first aid and sort out the injured.
Fire department officials said more than 70 people were in the building at the time of the fire and many of them ran outside.
Kyoto Animation, better known as KyoAni, was founded in 1981 as an animation and comic book production studio, and is known for mega-hit stories featuring high school girls, including Lucky Star, K-On! and Haruhi Suzumiya.
The company does not have a major presence outside Japan, though it was hired to do secondary animation work on a 1998 Pokemon feature that appeared in US theatres and a Winnie The Pooh video.
“My heart is in extreme pain. Why on earth did such violence have to be used?” company president Hideaki Hatta said.
Mr Hatta said the company had received anonymous death threats by email in the past, but he did not link them to the attack.