Swiss police said on Monday that they had arrested a 43-year-old suspect in relation to a deadly shooting incident at a rave in the town of Aarau on the weekend.A ‌22-year-old Italian ⁠woman ⁠was killed and five people injured after the ​shooting at the event at a covered horse race ​track in the early hours of Sunday morning.Police launched a massive operation and ​just before 1am on Monday ⁠arrested a ‌43-year-old Swiss man on ​suspicion of ​carrying out the attack, it ⁠said.Read more: Manhunt underway after woman killed, several injured at Switzerland rave shooting"Investigations into the exact circumstances of the ​incident, as well as its ​background and possible motive, are currently underway. At this stage, it is assumed that a single perpetrator was involved," police in the canton of Aargau said ‌in a statement.Police on Sunday said they were investigating three possible ​motives for ​the shooting, ⁠including a mass shooting, an act of terrorism or an unknown criminal motive.Read more: Manhunt underway after woman killed, several injured at Switzerland rave shootingCartridges found at the crime scene indicated two calibres of bullets, possibly from a pistol and a second, larger weapon, potentially an assault rifle, police said.