The three-year-old was on the sidewalk with his pedal-roller – the tragic accident happened in front of a garage exit.In the area of the exit of a garage in Hartlgasse, the three-year-old was pushed down by the car at 12.30 p.m. The boy suffered life-threatening injuries, as the Vienna police reported.An emergency doctor, who happened to be at the scene of the accident, took care of the boy until the rescue was on the spot. Vienna's professional…