The other 33 girls were injured and taken to hospitals, 10 of them in critical condition, reports say.
The girls, mostly of junior high school age, are from southern Roudan and were to participate in a national conference of talented students in Shiraz.
With some 17,000 annual deaths, Iran has one of the world's worst traffic safety records, often blamed on a combination of disregard for traffic laws, unsafe vehicles and inadequate emergency services.
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