Austrian troops stopped and searched a minibus at the border with Hungary and the driver of the vehicle fled the scene, police told AFP on Tuesday.
All the survivors were men, most of them from Syria, the Austrian APA news agency reported. The coach’s driver was being sought by police.
The incident recalled a dire event in August 2015 when 71 migrants from Syria, Iraq and Afghanistan suffocated in the back of an air-tight van where they had been hidden by people smugglers.
In that incident the bodies, including those of three children and a baby, were discovered in Austria but they died while still on the other side of the border.
Almost four years later, the Hungarian courts sentenced their smugglers to life imprisonment.
The emotion aroused by that tragedy triggered a brief opening of the borders to hundreds of thousands of people wishing to reach Western Europe, at the beginning of the 2015-2016 migratory wave.
Austria’s ex-chancellor Sebastian Kurz has held a tough line against migration, which looks likely to continue under his successor and former Foreign Minister Alexander Schallenberg.