Aarau (Switzerland) (AFP) - Swiss police were on Sunday hunting at least one gunman who opened fire at a rave, killing an Italian woman and wounding five other people, some of them seriously.

The shooting, which happened in the early hours in Aarau, near Zurich, and sent partygoers running for cover, is a rare event in the Alpine nation, despite widespread gun ownership.

The last major shooting occurred in 2001, when 14 members of the parliament and local government of the canton of Zug, near Lucerne, were killed by a gunman who then took his own life.

According to local media, shots were fired before 3:00 am (0100 GMT) near the Aarauer Rave, an annual techno party attended by some 3,500 people at the Aarau racetrack from Saturday afternoon to Sunday morning.

“A 22-year-old woman died of her injuries at the scene,” local police announced on X. “Four men and one woman, aged between 24 and 27, were taken to hospital. They are suffering from injuries ranging from minor to serious.”

Italy’s government said the killed woman was Italian, with Prime Minister Giorgia Meloni naming her as Maria Spinelli.

Italy’s foreign ministry said two other Italians were lightly injured in the shooting. Officials from its embassy in Switzerland went to the scene “to closely follow the investigation”, the ministry added.

All of the victims were Swiss residents, police said.

- Armed officers widely deployed -

Investigators are still in the dark about the attacker or attackers, police spokesman Bernhard Graser told reporters.

“For the moment, we have no reliable information regarding the perpetrators. We do not know whether it is a single person or several, nor whether they fled in a vehicle or on foot,” he said.

The area of the shooting remains sealed off Sunday as officers search for clues and interview eyewitnesses.

Aargau cantonal police commander Michael Leupold said investigators had found evidence of two different calibres, from a pistol or submachine gun, and an assault rifle.

He said the shots had been fired from two locations, at the rave itself and from next to a trailer park.

Leupold said police are working on three hypotheses: “The first is a terrorist attack, the second a mass killing, and the third a simple criminal act, the motive for which remains unknown.”

An AFP journalist saw armed officers deployed at the scene, the railway station and on the highway up to 30 kilometres (18 miles) away.

With the German border just a few dozen kilometres away, the investigation is being carried out in cooperation with Freiburg police, the DPA agency reported.

- ‘Several shots’ -

Media reports said an army helicopter was deployed in the cantonal capital, Aargau, as well as numerous police officers, rescue workers and medical teams.

Witnesses told Blick newspaper that shots were fired at about 2:30 am while the rave was still taking place. Initially, they were believed to be fireworks but one witness reported “shots fired in bursts”.

Many people sheltered in a nearby gymnasium for safety.

Swiss DJ Tekibo, who performed at the rave, wrote on Instagram that he was physically unharmed but deeply affected by the tragedy, in which he said he had lost a friend.

“Techno and raves are supposed to be spaces of freedom and safety, never places where something like this happens,” he said, calling the events “absolutely heartbreaking”.

A local resident in Aarau posted a video on social media showing deserted streets and what sounded like several gunshots in the background.

The Aargau cantonal police urged people to stay away from the area but asked for video recordings or photos from the rave.

Army reservists in Switzerland are allowed to keep their weapons, but not ammunition, at home. As a result, weapons are widespread but with no federal register it is difficult to know exactly how many.

According to the Geneva-based research centre Small Arms Survey, civilians had more than 2.3 million firearms in 2017 – nearly three for every 10 inhabitants.

That made Switzerland the 16th country in the world in terms of weapons per capita.