No other vehicles were involved in the crash, and it wasn't clear why the bus crashed into the overpass support column on the highway near Verona just before midnight, said police commander Girolamo Lacquaniti.

The bus was returning to Budapest with students aged 15 to 17. The impact of the crash was so strong that some passengers were thrown out the bus, RAI state radio said.

Sixteen badly burned bodies were pulled from the wreckage. Of the 39 survivors, 26 were injured, some seriously, Lacquaniti said.

The 13 who didn't need medical attention were resting at the highway police station, he said.

In Budapest, the foreign ministry said official information was that there were 54 passengers, including adults accompanying the students, and two drivers aboard, but it believes the actual number was higher — for reasons yet to be determined.

This corrects spelling of Girolamo Lacquaniti.