Zurich police on Monday were investigating a weekend incident in which a drone scattered banknotes over a crowd that had been drawn to an open area through social media.
The ensuing crush resulted in serious injury to a 12-year-old boy.
A Zurich police spokesman said that the person behind the event, which took place on Saturday, was known to them and was a well-known personality.
Media reports said that a person with a public profile on the Tiktok video platform had pre-announced the event, drawing people to the open area. Banknotes to the value of more than €20,000 ($21,500) were to be released, according to the Tiktok posting.
The spokesman said police were investigating how heavy the drone was, how high it flew and whether the organizer needed a licence. Several rules were potentially infringed, including the flying of drones over crowds.
In addition, events drawing large numbers of people require permission, and no permit had been applied for in this case.
The open area on Lake Zurich tends to draw hundreds of people when the weather is good, the spokesman said. With the appeal on Tiktok more people than usual were likely out and about there.