Iran's state TV says a bus carrying Shiite pilgrims has crashed, killing 26 people and wounding 16 others.

It says Wednesday that the bus overturned in the south of the country overnight, and that the cause is being investigated.

The bus was carrying Iranian pilgrims from the city of Yazd who were traveling to the Iraqi shrine city of Karbala for the Arbaeen religious observance.

Tens of thousands of Iranians are expected to attend the Nov. 20 ceremony in Karbala.

Road accidents kill an estimated 17,000 people a year in Iran, where many drivers ignore traffic laws, and where emergency services are lacking.