Swiss police have arrested a man in relation to a deadly shooting at a rave in the town of Aarau over the weekend. The as-yet-unnamed man, 43, was arrested just before 1am on Monday after a 22-year-old Italian woman was killed and five people were injured in the early hours of Sunday morning at the techno event, held at a covered horse-racing track. 'Investigations into the exact circumstances of the incident, as well as its background and possible motive, are currently under way. At this stage, it is assumed that a single perpetrator was involved,' police in the canton of Aargau said in a statement. They gave no further details today, but said on Sunday they were investigating three possible motives including a mass killing, an act of terrorism or an unknown criminal motive.The young woman who was killed was named as Maria Spinelli by Italy's prime minister Giorgia Meloni. Four men and one woman, aged between 24 and 27 were hospitalised with injuries ranging from minor to severe. Ms Meloni identified Ms Spinelli and two other victims as Italian citizens on Sunday evening.'I express my deepest condolences for the death of Maria Spinelli, the young Italian woman who was a victim of the tragic shooting in Aarau, Switzerland,' she wrote on X. Five others including four men and a woman were also injured alongside Maria Spinelli (pictured) who was killed The 22-year-old Italian national was killed at Aarauer Rave, a techno event held 29 miles west of Zurich Police cordoned off the area around the Aarauer Rave after one person was killed and five wounded in a shooting on Sunday 'My thoughts also go to the other injured individuals, among whom there are two Italian citizens, and to all the people involved in this dramatic event.'Ms Meloni added that she trusts 'the work of the Swiss authorities to shed full light on what happened and identify those responsible'.Ms Spinelli reportedly moved to Switzerland just a month ago from the Abruzzo region in southern Italy to work as a waitress.Police spokesperson Bernhard Graser told reporters that 'several shots' were fired 'within a large group of people' at the Pferderennbahn Schachen Aarau horse racing track but investigators are still in the dark.'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.Asked whether a terrorist attack was a possibility, Graser said: 'The fact that the rave was already winding down suggests that's not the case. A fight could also be a possibility.' Cartridges found at the scene indicated two calibres of bullet, possibly from a pistol and an assault rifle, police said.The Swiss newspaper Tages-Anzeiger said cartridges found resembled those used in the Russian AK-74 assault rifle and its variants.As the investigations continued on Sunday afternoon, locals were asked to stay away from the area.Officers, firefighters and ambulances were on the scene in large numbers as well as police from neighbouring Freiburg, Germany, who took part in the mass search effort. Some 3,500 people attended the annual techno party, which took place in Aarau between 3pm on Saturday and 2am on Sunday. Maria Spinelli was shot and killed at a rave in Switzerland in the early hours of August 30 Swiss officers searched for the gunman, whose identity they said was unknown, as an army helicopter circled the town Around 3,500 attended the rave, pictured in promotional material, held west of Zurich in northern SwitzerlandPartygoers first thought the shots were fireworks but soon fled to a nearby gymnasium from the racecourse where the rave was held, Swiss newspaper Blick reported. Others hid under the DJ booth as one attendee said there had been a 'burst of gunfire'.And an Aarau resident posted a video on social media showing deserted streets and what sounded similar to gunshots in the background.Tekibo, a DJ who performed a set at the rave, said on social media he had not been injured in the shooting but that he had 'lost an important friend'.'What happened at the Aarauer Rave is absolutely heartbreaking and something that should never happen at our scene,' he said.'Techno and raves are supposed to be a place for freedom and safety, never a place where something like this happens.'I'm still trying to process what happened cause I lost an important friend and don't have the right words for it.'Another DJ who performed at the rave, Sam Madi, said on Instagram he was also unscathed, adding the shooting had left him 'deeply sad'.Basel-based DJ duo Moodos also said they were not involved in the shooting and that they were 'shocked'.An army helicopter was reportedly sent to Aarau, capital of the Aargau canton – similar to a county – alongside police, rescue workers and medical teams.Armed officers were seen on highways up to 18 miles from the site of the rave.The Aargau Racing Club said in a statement: 'Our deepest sympathies go out to all those affected and their families who find themselves in this difficult and distressing situation.'The exact circumstances of the incident are currently being investigated with the utmost care.'At this time, no definitive information regarding the background of the incident is available.'Shootings are rare in Switzerland despite widespread gun ownership, though laws have been tightened in recent years.The country's last major shooting was in 2001, when 14 members of parliament and local government in the canton of Zug, near Lucerne, were killed by a gunman who then took his own life.According to the Geneva-based research centre Small Arms Survey, civilians had more than 2.3 million firearms in 2017 – nearly three for every ten inhabitants.That made Switzerland the 16th country in the world in terms of weapons per capita.