PARIS - Two rounds of gunfire have hit a bus carrying Czech tourists through southeastern France, injuring six passengers.

The prosecutor of Valence, Alex Perrin, says the bus was hit Friday night as it traveled along the A7 highway on its way home from a trip to Spain.

Six of the passengers, which included school children, were slightly injured after being hit by flying glass and one person was seriously hurt.

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Perrin told BFM-TV that a first shot hit the front window and a second hit the rear window, shattering both.

There have been no arrests, claims of responsibility or even conjectures about the motive.

Perrin said "one could think that this bus ... was no more a target than any other."

BBC reports officials suspect the gunman was "using a hunting rifle to target the bus from a bridge over the A7 motorway near Saulce sur Rhone, roughly halfway between Lyon and Marseille."

France has been on high alert after recent terrorist attacks in Paris, Belgium, and elsewhere.