A suspected arson attack on an animation production company in Japan killed at least 20 people, 10 more feared dead and injured dozens more on Thursday, with flames gutting the building in the city of Kyoto. Police said the fierce blaze appeared to have been started deliberately but there was no immediate information on a possible motive. Local media reported that a 41-year-old suspect had poured gasoline on the building before setting fire to it. Police also found knives at the scene. The toll continued to climb hours after the fire began, with fire department officials saying bodies were being discovered as they searched the ravaged building. A Japanese fire official said nearly 30 people have been confirmed or presumed dead in the suspected arson and Kyoto fire department official Mikihide Daikoku said 36 others have been injured, some of them critically. Japanese Prime Minister Shinzo Abe wrote on Twitter that the attack was "too appalling" for words and offered his condolences to the victims. Footage of the blaze showed thick white smoke pouring from the windows of the three-storey building. Its facade was charred black on much of one side where the flames had shot out of the windows. The fire department said it began receiving calls around 10:35 am (0135 GMT) about the fire at the studio belonging to Kyoto Animation. "Callers reported having heard a loud explosion from the first floor of Kyoto Animation and seeing smoke," a fire department spokesman said. Police said they were still investigating the cause of the fire but it was a suspected arson attack. "A man threw a liquid and set fire to it," a Kyoto prefectural police spokesman told AFP. Public broadcaster NHK reported that a man had been detained in connection with the blaze and was later taken to hospital for treatment. It reported that the suspect had poured a gasoline-like substance around the building and said "drop dead" as he set fire to it. The president of the popular Japanese animation production company said his company has received anonymous death threats. Hideaki Hatta, head of Kyoto Animation, told reporters the company had gotten threats by emails in the past but responded "sincerely" each time. Mr Hatta asked, "Why on earth did such violence have to be used?" There was an outpouring of support for the studio on Japanese-language social media, with some users posting pictures of animation. Many posted with the hashtag "£PrayForKyoani" – using an abbreviation for Kyoto Animation. Violent crime is relatively rare in Japan but occasional high-profile incidents have shocked the country.