RIO DE JANEIRO, Brazil (AFP) — Brazilian football was in mourning on Friday after 10 people died when a fire ripped through a youth training facility at the country’s most popular club, Flamengo, authorities said.

The pre-dawn blaze in Rio de Janeiro hit a building that housed players aged 14 to 17, firefighters said.

Rio’s deputy governor, Claudio Castro said “preliminary information indicates there were young players and staff” amongst the dead.

The SporTV channel said the victims included six players and four members of staff.

Distraught relatives rushed to the facility seeking information about loved ones, TV footage showed. Most of the youth players at the club are not locals but come from all over the country.

In addition to the deaths, three people were injured.

The cause was not immediately known, but local newspaper Extra said witnesses alleged the fire started in the air conditioning system.

“It’s the worst tragedy in the club’s 123 years,” said Flamengo president Rodolfo Landim, who visited the scene.

“Flamengo is in mourning,” the club wrote on its social media accounts.

Brazil’s President Jair Bolsonaro, who is in semi-intensive care in hospital following surgery on his abdomen, said he felt “the families’ pain.”

In a statement shared by the presidency, he added that he was dismayed by “this tragedy… which has taken the lives of young people who had started the journey towards realizing their professional dreams.”

Brazil’s Pele, widely regarded as the best player to ever live, said: “It’s a very sad day for Brazilian football.”

The country’s biggest current star Neymar, who plays for Paris Saint-Germain in France, posted a picture on his Instagram account of the Flamengo club badge with the words: “My sympathies.”

Teenage Real Madrid forward Vinicius Junior, who came up through the youth ranks at Flamengo before signing with the European Champions in 2017 for 45 million euros (US$51 million), posted a message on Twitter asking people to pray for the victims.

“Just by thinking about the days and nights I spent in the training centre gives me goose bumps,” said the 18-year-old.

“I still can’t believe it. Let’s pray for everyone.”

Globo TV broadcast aerial footage of the fire, which it said had been brought under control after it burned for two hours.

The blaze broke out at 5:00 am in the Vargem Grande district of Rio in a modern facility where the top-flight professional Flamengo squad also trains, the news website G1 said.