A suspected arson attack on an animation production company in Japan killed 13 people 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.
There were fears the toll could rise further, with officials saying they believed several more people had failed to escape the fire.
"Twelve people were found in cardio-respiratory arrest on the ground and first floor," a fire department official told AFP, using a phrase commonly employed in Japan to signify victims have died but their deaths have not yet been officially certified.
Officials had already confirmed one death earlier in the blaze.
"Also, several other people appeared to have failed to escape on the second floor," he added.
Officials said 35 people had been injured in the fire, 10 of whom were in serious condition, and local media said around 70 people were believed to have been in the building when the fire started.
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.
"Rescue operations are continuing, and we are trying to bring out several victims who are trapped inside... including ones who may not be able to move by themselves," a second fire department spokesman said.
"We can't immediately determine their condition," he said.
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.
Witnesses described a powerful blaze.
"I heard two loud bangs, they sounded like explosions," a man told NHK
"The fire was raging hard. I saw red flames flaring."
A woman living nearby told Kyodo news agency she had seen 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.
There was no immediate statement from the studio, which produced several well-known television anime series, including "The Melancholy of Haruhi Suzumiya" and "K-ON!"
"We are in the process of learning what happened," said a woman who answered the phone at the firm's headquarters in Uji City in the Kyoto region.
"We cannot tell you anything more," she added.
The blaze prompted an outpouring of support from those in Japan's anime industry, one of the country's best known cultural exports.
"No, I don't know what I should be thinking now," tweeted Yutaka Yamamoto, an animation director who once worked at Kyoto Animation.
"Why, why, why?"
Japan has a famously low crime rate, with violent crime very rare.
Arson is considered a serious crime and people convicted of deliberately setting fires in a country where many people still live in wooden houses can face the death penalty.
A man convicted of setting a fire that killed 16 people in Osaka in 2008 is currently on death row.
Tokyo, Japan | AFP