“I’m writing this from my dressing room in the stadium. The decision has been made to postpone tonight’s show due to the extreme temperatures in Rio,” the singer said in a handwritten note on Instagram. “The safety and well being of my fans, fellow performers, and crew has to and always will come first.”

The cause of death for Ana Clara Benevides Machado, the young woman who sought medical attention at Nilton Santos Olympic Stadium during Friday’s show, has not yet been announced. The office of Rio’s public prosecutor opened a criminal investigation and said Benevides’ body was being examined.

Benevides’ death shook many people in Brazil. She had taken her first flight ever to travel from the country’s center-west region to Rio to see her favorite musician. She also created a WhatsApp group to keep her family updated, sending photos and videos every step of the way, family members told online news site G1.

Fans and politicians reacted to her death with outrage, speculating it was linked to extreme heat.

Concertgoers complained they were not allowed to take water into the stadium despite the stifling weather. As temperatures continued to rise Saturday and with two more shows to go at the time, federal authorities announced that free water would now be made available at concerts and other large events.

One of Benevides’ friends, who also went to the concert, told local outlets they had both been given water while waiting to enter the stadium.

In a previous statement shared on her social media Saturday morning, Swift said she had a “shattered heart.”

“There’s very little information I have other than the fact that she was so incredibly beautiful and far too young,” the singer wrote of the young woman.

The show’s organizer, Time4Fun, said on Instagram that paramedics attended to Benevides after she reported feeling unwell. She was taken to a first-aid center and then to a hospital, where she died an hour later, the statement from the Brazilian live entertainment company said.

Fans who attended the Friday show said they were not allowed to bring water bottles into the stadium even though Rio and most of Brazil have had record-breaking temperatures this week amid a dangerous and lasting heat wave. The daytime high in Rio on Friday was 39.1 degrees Celsius (102.4 degrees Fahrenheit), but it felt much hotter.

Apparent temperature — a combination of temperature and humidity — hit 59 C (138 F) Friday morning in Rio, the highest index ever recorded there.

Elizabeth Morin, 26, who recently moved to Rio from Los Angeles, described “sauna-like” conditions inside the stadium.

“It was extremely hot. My hair got so wet from sweat as soon as I came in,” she said. “There was a point at which I had to check my breathing to make sure I wasn’t going to pass out.”

Morin said she drank plenty of water but saw “a good amount of people looking distressed” and others “yelling for water.” She said she was able to get water from the sidelines of the area she was standing in, but that water was a lot harder to access from other parts of the stadium, “especially if you were concerned about losing your specific position.”

During the show, Swift paused her performance and asked from the stage for water to be brought to a group of people who had successfully caught the singer’s attention, according to Morin.

“They were holding up their phones saying ‘We need water,’” she recalled.

Two other concertgoers interviewed by The Associated Press said they witnessed people feeling unwell from the heat during the show.

On her way to Rio, Benevides sent a video to family members that was broadcast by TV channel Globo News, telling them: “Mom, look at the plane, it’s moving. Mom, I’m on the plane. My God in heaven! I’m happy!”

Then before the concert, she posted a video of herself on Instagram wearing a Taylor Swift T-shirt and friendship bracelets, seeking shade under an umbrella while waiting in line to enter the stadium.

Like her, thousands of fans waited hours in the sun before being allowed inside.

She told her followers while fanning her face that she’d arrived at 11 a.m. — the show began around 7:30 p.m. — and was “still in the mess.”

Benevides’ friend, Daniele Menin, who attended the concert with her, told online news site G1 that her friend passed out at the beginning of the concert, as Swift performed her second song, “Cruel Summer.”

“We always said that when (Taylor Swift) came to Brazil we would find a way to go. The ticket was very expensive, but we still found a way,” Menin told G1.

Justice Minister Flávio Dino said on X, formerly known as Twitter, that going forward in Brazil, “water bottles for personal use, in suitable material, will be allowed” at concerts and festivals and that show producers must provide free and easily accessible drinking water.

Rio de Janeiro Mayor Eduardo Paes wrote on X that the “loss of a young woman’s life … is unacceptable” and demanded more brigades and ambulances at future shows.

Still, the concert was postponed.

“We are on the train. And everyone is so disappointed,” said Hely Olivares, a 41 year-old Venezuelan who had traveled from Panama to see the artist.

Before postponing the concert, Swift wrote on Instagram that she would not address the death from stage “because I feel overwhelmed by grief when I even try to talk about it.”

“I want to say now I feel this loss deeply and my broken heart goes out to her family and friends,” she said.