The shooting triggered a large-scale police operation in the area as authorities launched a search for those responsible.

Shots fired near racecourse

The incident took place at the racecourse where the annual Aarauer Rave was being held, according to local media.

Police spokeswoman Vanessa Rumpold said several shots were fired among a large crowd. A witness also reported hearing multiple bursts of gunfire.

According to Swiss newspaper Blick, the shooting occurred before 3 am local time (0100 GMT) on Sunday, shortly after the main event had ended.

Around 3,500 people attended event

The annual techno party drew around 3,500 attendees between 3 pm on Saturday and 2 am on Sunday.

The shooting occurred at the venue shortly after the event's scheduled closing time, although authorities have not yet provided details about what led to the violence.

Motive, suspects still unknown

Police said the identities of the suspected perpetrators were not yet known and that a search was underway to locate them.

"The search for the perpetrators, whose identities are currently unknown, is under way," police said, adding that the motive and exact circumstances of the shooting remain unclear.

Investigators are expected to examine the events leading up to the shooting as they work to establish what happened and identify those responsible.