As the Russian pop group, Mango Mango, played their closing number, the heavens opened over the Belarussian capital and lightning struck.
Within minutes, on a quiet Sunday evening, dozens of young people were dead and many more injured, crushed in a stampede in a tunnel to Nyamiha underground railway station as they sought shelter from the thunderstorm that broke over their beer festival.
Officials said yesterday that 54 people died, many of them teenaged women in high heels who slipped on the wet marble steps into the underpass, and 150 were injured. Many people had been drunk, the Interior Minister, Mr Yuri Sivakov, said.
However, Belarus President Alexander Lukashenko said heavy drinking had not been the cause of the accident. "We should not be looking for the cause in drunkenness," he said.
"I ask our nation not to judge or blame the dead," he added in a national address.
Most of the victims died of suffocation. Forty-four of those killed were women. Two police officers who were trying to rescue the survivors also died in the rush, NTV television reported.
Nearly 90 people were still in hospital yesterday, 37 of them in critical condition, city officials said.
"First one person fell, then others, and the crowd thought it was just for fun so they jumped on top of them," said one witness, Mr Tsezari Golinsky. "Then they started screaming but no one in the back paid any attention.
"There were lots of drunk people around. Some continued drinking after what happened just 100 metres away from the station."
Dmitry (23), a student, said, "A woman was going up the steps leading out of the metro station when the running crowd threw her headlong down the steps. I saw her corpse being removed later on."
Another young man in his mid20s, Andrei, said panic had spread through the crowd after a powerful bolt of lightning flashed overhead as the group played one of its popular jaunty songs.
He said he survived because he did not head for shelter right away from the small square near the Sports Palace in the centre of Minsk, the spacious, Soviet-style capital of Belarus.
"We had a sleepless night after seeing this nightmare," Andrei said, recalling the scene in the underpass. "We just drank vodka."
Yesterday, a crowd of more than 100 distraught local people - many of them relatives and friends of those caught in the crush - gathered at the entrance to the metro station in grim silence. Many were crying.
On radio and television, brief news bulletins were interspersed throughout the day by mournful classical music. President Lukashenko declared two days of mourning.
As in similar Soviet-era systems in Russia and Ukraine, slippery polished marble was frequently used for stairs and other architectural details of Belarus's two-line metro system, especially in the centre of the city.
Trucks and buses took the bodies away as ambulances and private cars ferried the injured to hospital.
"It's a frightening tragedy," Mr Lukashenko said at the scene, his hands clasped in front of him, his head slightly bowed. "For Belarus it is something unreal . . . for the first time I find it difficult to know what to say."