“I don’t really know if it really happened, but I saw desperate people running,” Mr. Duarte said. “And as soon as I saw it, I started running along and hid in a car park.”

On Sunday, the military police said there had been no reports of robberies or muggings the night before. But before the concert on Sunday, a fan in Rio de Janeiro for the concert was stabbed to death after an attempted robbery in Copacabana, the famous beachside strip, the military police said. Two men had been arrested, they said. The man, Gabriel Mongenot Santana Milhomem Santos, was with friends when he was stabbed, the civil police said.

During Friday’s show, Ana Clara Benevides, 23, died after losing consciousness, officials said. She was pronounced dead of cardiac arrest after being taken to a hospital, according to city officials and the Brazilian company that organized Ms. Swift’s show, Time for Fun.

Ms. Benevides, a psychology student, had traveled from Rondonópolis, which is about 880 miles northwest of Rio de Janeiro, for the concert, O Globo reported. Her friend Emiliane Félix, 22, told O Globo that Ms. Benevides had been sending her friends photos of her outfits for the concert “for over a month.”

On X, the social media platform formerly known as Twitter, Ms. Benevides shared her excitement about the concert, writing on Nov. 7, “I don’t know what my purpose in life will be after I see Taylor.”