Cantonal police in Aargau said a large-scale operation was underway and they appealed to the public for any film or pictures of the incident, which the mass-market Blick tabloid said occurred at a rave party, Reuters reported.

The newspaper published video footage, taken from an elevated position, it said had come from a reader showing a night-time street scene with the sound of several shots being fired.

No further details were immediately available.