MOSCOW (Sputnik) — Preliminary indications suggest that they suffocated after being trapped inside the vehicle, the Kronen Zeitung daily reported.
Austria's Interior Ministry has not commented on the tragedy so far.
Later on Thursday, state authorities from Germany and Western Balkan countries are expected to discuss measures to counter the refugee crisis during a summit in the Austrian capital.
According to the European Union's external border protection agency Frontex, the total number of refugees detected at the bloc's borders between January and July 2015 stands at over 340,000, which is three times higher than during the same period in 2014.
