A 59-year-old man who was walking in an adjacent park at around 6 pm felt a sharp pain in his back. His wife later observed two small red marks.
At least three other people noted similar symptoms, and a witness informed police that two young men appeared to be using some sort of weapon from a nearby apartment.
After finding the source of the shots, the two would-be snipers were arrested, and will be charged with weapon-related offences.
The pair explained that they shot at people because they were "bored".
Police seized two weapons, both of which are gas-powered.
In general, gas-powered weapons are freely available in Austria. A similar case occurred in 2013, when a pair of teens were caught shooting at pedestrians from one of their mother's car.
In that case, the pair were forced to apologise to their 18 victims, and received a suspended sentence of 14 months.