The bus was carrying passengers from Kosovo to Munich when it collided with another wreck between two trucks just after midnight on the A21 motorway near Vienna. While the bus did not overturn, the extreme impact lead to the high number of victims, a police spokesperson said.
The driver and passengers from the first few rows were killed, while seven of the 20 injured were in critical condition after the accident, he added.
Most of the 38 passengers on the bus were reportedly from Serbia and Kosovo.
Rescue services were out in full force to help, and the road was closed until 7 am in both directions. The injured were transported to several different hospitals near Vienna.
The cause of the accident remains under investigation. Initial media reports said the motorway was icy, but a spokesperson from the autobahn operator denied this in the early morning, explaining that the road was dry after the sun had shined the entire day before.