Iran's state news agency says at least 19 people have been killed in the country's south after the bus they were travelling on struck a rock and flipped over.
IRNA says the accident took place Sunday some 50 kilometers (30 miles) west of the southern Iranian city of Shiraz.
It says around 25 passengers were injured and transferred to local hospitals. Five of them are in serious condition.
Iran has one of the worst road safety records in the world. Statistics say that more than 20,000 people lose their lives in road accidents every year in the country.
The high toll is blamed on disregard of traffic rules, unsafe roads and poor emergency services.