Authorities have found 53 people apparently headed for Germany crammed into a small truck that was stopped in the Austrian city of Linz.
Four men were in the cabin of the vehicle when it was stopped on Sunday morning, one of whom fled on foot after getting out of the vehicle, police said.
He was arrested, as were three others, on suspicion of smuggling.
In the truck's cargo compartment, officers found the 53 people, including small children.
Most of them were from Turkey, police said.
The smuggling suspects were three Turkish citizens aged between 18 and 28 and another man whose identity has yet to be established.
Police did not give details of the migrants' journey but in recent years authorities have repeatedly found large numbers of people crammed into vehicles that brought them across the Balkans to Austria.