A 43-year-old Swiss man was arrested early Monday on strong suspicion of carrying out a shooting at an annual rave in Aarau, the capital of Switzerland’s northern canton of Aargau. The attack occurred in the early hours of Sunday as the event was winding down, leaving one person dead and five others injured.

According to police, the victim who died was a 22-year-old Italian woman who succumbed to her injuries at the scene despite resuscitation efforts. The five others wounded included four Swiss men and one German woman, aged between 24 and 31, who were hospitalized with injuries ranging from minor to serious.

The shooting prompted an international manhunt before the suspect’s apprehension shortly before 1 a.m. Monday. Authorities said the investigation was ongoing to determine the exact sequence of events and the motive behind the attack. It is believed that a lone perpetrator was involved.

Police have recovered evidence indicating the use of two different calibers of firearm, possibly including a pistol or submachine gun and an assault rifle. Aargau police chief Michael Leupold stated that investigators were considering three main hypotheses: a terrorist attack, a mass shooting, or a criminal act with an as-yet unknown motive.

The incident has drawn attention beyond Switzerland, with Italian Prime Minister Giorgia Meloni confirming that two Italians were among those injured. However, Swiss police maintained that the wounded comprised Swiss nationals and one German citizen.

Authorities continue to gather information as they work to clarify the circumstances surrounding the rare deadly shooting at the event.