Gunman arrested after deadly shooting at Switzerland rave left one dead and several injured

The individual is yet to be identified.

A 22-year-old Italian woman was killed, and five people in their 20s were injured in the attack.

All victims are Swiss residents, police in the town of Aarau said.

Italy's Prime Minister Giorgia Meloni named the woman killed as Maria Spinelli.

She wrote on social media: "My thoughts also go to the other injured, including two Italian citizens, and to all the people involved."

Italy offered its support with the investigation.

Swiss police previously admitted that they were in the early stages of the investigation and did not yet know how many attackers there were or what their motives were.

The police did not rule out the possibility of the alleged attack being an act of terrorism.

Aargau's Police Commander Michael Leupold told reporters: "The end is not in sight.

"Where an active shooter is firing into a crowd of thousands of people at an event, it's perfectly clear that we consider terrorism as a motive."

A 34-year-old witness who asked for anonymity told reporters he heard shots shortly after the music stopped at 2.30am local time, which he initially mistook for fireworks.

Some people took cover behind a DJ booth and one woman hid behind a refrigerator, but was hit in the back by a bullet and bled to death despite efforts to revive her.

The witness said: "It's just incredibly tragic. She was young...That something like this could happen in Aarau, at a local event, is simply unimaginable. I still can't really process it."

Cartridges found at the crime scene indicated two calibres of bullets, possibly from a pistol and a second, larger weapon, potentially an assault rifle or machine gun, police said.

The organisers' website advertised the event as a techno party at a covered horse racetrack, with 3,500 people expected to attend.

Organisers said they were shocked and heartbroken by the incident.

"A rave should always be a place of joy and love, never a place where people are killed, injured, or left in fear," they said.

Switzerland has one of the highest rates of gun ownership in Europe, although violent shootings are rare and it approved tighter gun control rules in 2019.