A fire has engulfed a dormitory at the youth team training centre of one of Brazil's biggest football clubs, killing 10 teenage players.
The victims were all staying at Ninho de Urubu, the training ground of Flamengo football club in Rio de Janeiro.
Three teenagers were also injured, one of them seriously. He has been taken to hospital for specialist treatment.
An investigation has been launched into the cause of the blaze.
However, local media report that the accommodation area was officially licensed by the state as a car park.
One young player said the fire started in an air conditioner in his room.
"The air conditioner caught fire and I ran out," said Felipe Cardoso, a player with the under-17 side. "Thank God I managed to run and I'm still alive."
Flamengo is one of Brazil's biggest and best-known clubs internationally. They play in the Campeonato Brasileiro Série A league where they finished in second place last season.
Club president Rodolfo Landim told reporters this was "without a doubt the worst tragedy this club has been through" in its 123-year history.
"The most important thing now is for us to try to minimise the pain and suffering of these families".
Brazil football legend Pelé described the club as "a place where young people pursue their dreams".
"It's a very sad day for Brazilian football," he tweeted.
Brazilian star forward and Paris Saint-Germain player Neymar posted the club's crest on Instagram, writing: "My sentiments."
President Jair Bolsonaro, who is receiving treatment for pneumonia, tweeted a statement from the hospital "in solidarity" with the mourning families.
He said the tragedy made victims of young people "on the journey to realising their professional dreams".
Who were the victims?
Local media have published the names of the victims, all of whom were aged between 14 and 16:
- Arthur Vinicius Silva
- Áthila Paixao
- Bernardo Pisetta
- Christian Esmerio
- Vítor Isaías
- Pablo Henrique
- Jorge Eduardo
- Samuel Thomas
- Gedson Santos
- Rykelmo Viana
Senior club goalkeeper, Gabriel Batista, posted on Twitter about youth keeper Christian Esmerio.
"I had the pleasure of knowing you," it reads. "God receive you with open arms".
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One of the three injured, a 15-year-old boy, suffered severe burns.
Folha newspaper named him as Jonathan Cruz Ventura, who doctors say was burned on 30% of his body.
What do we know so far?
According to the G1 news portal, the fire began at 05:10 (07:10 GMT) and was extinguished by 07:30.
Fire service Lt Col Douglas Henaut told reporters that rescuers managed to save victims outside the building, but "we only found bodies inside".
"The place was completely overtaken by fire," he said.
The area has been hit by severe storms and heavy rain in recent days and the weather may have left the facility without water or electricity when the fire struck, G1 reported.
Local media reports suggest the fire happened in an older part of the centre that was scheduled to be torn down.
UOL Sports reports that Rio de Janeiro council issued a statement saying the last licence issued for the area where the accommodation was sited was for a car park, and was valid until March 2019.
It is unknown if there were smoke alarms present.
Flamengo's pride in youth academy
Analysis by Fernando Duarte, BBC Brasil
Flamengo are one of the few Brazilian clubs that can boast an expressive national fan base in Brazil. A poll released last April suggested they are the first team for 32.5 million Brazilians.
The club owes a great chunk of this support to an incredible run of four Brazilian titles and a victorious Copa Libertadores campaign (the South American version of the Uefa Champions League) in the 1980s.
It has also produced arguably one of the greatest all-time Brazilian players - Arthur Antunes "Zico" Coimbra, a member of the 1982 World Cup squad that failed to win the title but won worldwide plaudits for its slick style.
The club is also proud of the tradition of its youth academy - its motto is "we make our star players at home" - which will make this tragedy even sadder.
Who are Flamengo?
The club's most prominent former players include World Cup winners Ronaldinho, Bebeto and Romario.
As well as being one of Brazil's most successful football clubs, Flamengo also has basketball, rowing, swimming and volleyball teams.
In a tweet on Friday, the team said it was "in mourning".
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The Ninho de Urubu ("Vulture's Nest" - so named because the symbol of the club is a vulture) centre underwent a major expansion last year, with the club spending 23m reais (£4.8m, $6.2m), Reuters news agency reports.
The site features accommodation for young players, several pitches, an aquatic park, a gym, a medical centre and a mini stadium.
The team were due to play their rivals Fluminense on Saturday. The game has been postponed, and other clubs have expressed their condolences.
Real Madrid player Vinícius Júnior, who also played for Flamengo, tweeted a crying emoji, writing, "Such sad news. Pray for everyone. Strength strength, strength."
Ronaldinho offered his condolences for the "terrible tragedy" in a tweet on Friday morning. He published the club's crest in black-and-white.
Just over two years ago, Brazil's football world was rocked by disaster when a plane carrying top football team Chapecoense crashed in Colombia.
Of the 77 people on board, 71 lost their lives.