AARAU — At least one person was killed and five others injured after shots were fired at an event attended by around 3,500 people in the Swiss town of Aarau early Sunday, police said.Some of the injured were in serious condition, according to Aargau cantonal police, which launched a large-scale operation following the shooting.Police said they were searching for the person or people responsible, while the motive and circumstances surrounding the attack remained unclear.“Possible motives and the exact circumstances of the incident remain unclear,” police said, without providing details about potential suspects.A video published by Swiss newspaper Blick and reportedly recorded near the scene appeared to capture around 10 gunshots.Authorities urged the public to avoid the affected area while the police operation and search continued.A Swiss military Super Puma helicopter was also deployed over the wider Aarau area, according to Swiss emergency news outlet BRK News.Aarau is located about 40 kilometers (25 miles) west of Zurich.