Twenty-four people had been traveling on the minibus, including 17 children aged between 10 and 14.
In addition to three serious injuries, 13 people were lightly injured when the minibus veered off the road and fell into a four-meter ditch between Ronok and Vasszentmihaly.
The fire services had to be called to free one person from the wreck and psychologists have also been sent to the site, Tibor Dobson said.
The bus’s final destination was Venice, he said.