The incident occurred overnight in the province of Vorarlberg where around 150 people remained after the event, at which alcohol was consumed.
After getting into an argument, the man went back to his car and returned with a gun with which he began shooting people at random before killing himself, according to preliminary information.
The incident did not immediately appear to be linked to Sunday's presidential election runoff vote in Austria that could see a far-right candidate swept to power.
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