Young people are busy choosing clothing or finishing their hair before the Walpurgis Festival commemorates the beginning of spring. Not everyone is alive.

At a hair salon in Stockala in Uppsala, police said three young men, aged between 15 and 20, were shot dead before the celebration began.

Horror has caused many people to shake in the festival seats, known in Swedish as Valberg, which is usually the eve of every 30th of the 30th of the Christian Feast Day of St. Walburga. Uppsala is famous nationwide and hosts the country's largest and most highly-respected Walpurgis event, which is popular with students.

The party was indeed in full swing, but the delicate heaviness hung over Swedish blue and yellow flags that fluttered around the city.

Now, with the festival over, it's the only police video - not the flag - outside the basement barber shop near Waxara Square.

“It’s really sad,” said Yamen Alchoum, 20, a student who dined in a nearby food truck. He said he was in another barber shop at night in the shooting but had cut his hair several times before in the salon. "I think if I were there (Tuesday) … I would be involved in the shooting. It's a little scary."

Two young victims were sitting in a living room chair in a haircut shawl while talking to Swedish media TV4 and Aftonbladet, when they were shot in the head after 5 p.m. Tuesday, according to witnesses.

At the time, downtown was busy with commuters heading to a nearby train station, and students from the city's prestigious university returned to their apartment by bike.

Witnesses reported that when they heard loud bangs, many people mistakenly thought of fireworks. A few minutes later, several police cars and an ambulance arrived, blocking the streets and forcing a bus to turn around. Helicopters and drones were dispatched to try to track down the suspects. Local media reported that he had worn a mask and got rid of the scene with an electric scooter.

“I heard about helicopters, so I knew what was going on,” said Sara, 32. She said her cell phone quickly illuminated with news notifications and friends' text messages, asking her if she was okay.

About two hours after the shooting, police arrested a 16-year-old boy. In Sweden, suspects can be held based on different suspicions, and the teenager was initially held at the second highest level, indicating that people's suspicion is strong.

However, by Friday, prosecutors said the case against him had weakened and he was released.

Swedish police confirmed on Saturday that six people related to the case had been arrested. According to the state attorney's office, the age range of the suspects ranges from 18 to 45 years old, with someone suspected of committing a killing.

People visiting Uppsala for Wolburgis Festival are advised not to change their plans as police promise additional resources on the streets of Cathedral City and suggest that the shooting could be an “isolated incident.”

Despite many shaking, thousands of Swedes are still following their advice, packing the banks of the Fyris River in Uppsala, watching the annual student raft competition, drinking in city bars and parks, or heading to a large public bonfire at night. Others attended the annual spring ceremony where college and former students gathered outside the university.

"I'm really not afraid." Alvin Rose, a 19-year-old social studies student, said there was a snack in Vaksala Square, just around the corner of the shooting. “It feels like there is more security, more police.”

His friend Kassandra Fritz, an 18-year-old natural science student, said she had driven to Uppsala from her home in Gävle, two hours north to "have fun and meet new people."

She reflected that she no longer had a “strong” response to the shootings in Sweden because it was often headlines. “There have been a lot of shootings recently, not only in Uppsala, but everywhere in Sweden.”

Over the past decade, Sweden has become a European hotspot in gun crime, often associated with criminal networks. Research by the Swedish National Crime Prevention Commission concluded that the perpetrators are “growing younger” in imagery, with more and more teenagers committing or dying from gun violence.

Swedish Prime Minister Ulf Kristersesson traveled to Valencia at the time of the shooting in Uppsala, but has since described it as "extreme act of violence."

"This emphasizes that the wave of violence is not over yet," he said in an interview with Swedish news agency TT on Wednesday.

In a press conference the next day, officials said they were investigating the possibility of death related to gang crime, but said it was too early.

Police in various cities in Sweden have previously said that gangs contracting vulnerable children to commit crimes are becoming increasingly common because those under the age of 15 are lower than Sweden's criminal liability.

The Swedish government recently introduced controversial new legislation that would allow police to eavesdrop on children to prevent them from being recruited into teenage gangs.

Ministers also said they wanted to tighten the country's gun laws.

In February, the country's worst mass shooting was killed in an adult education center in Orebro, Sweden. In this case, police suspected that a 35-year-old murder was behind the killings. He legally possessed a weapon and was found dead in a building.

Yamen, 20, said he never involved gang crime outside of the hair salon in Uppsala, but knew a lot of others.

“A lot of times in my school, there was gang violence, on the streets – dealers,” he said. “But my personality is to work, study, and now I’m in college.”

As he left to meet his friend, the steady young man continued to stop on the corner next to the hairdresser, some bringing a bouquet of flowers. Several people were obviously shaking, and tears were flowing in their eyes.

"I know him very well," said Elias, 16, who said he was a friend of a victim and asked the BBC not to share his last name. "You know it doesn't feel real. It feels like I'm not really accepting this."