At least 24 students were killed Saturday when a tour bus they were riding in overturned on a highway in northern Iran, state-run radio reported.

The students were heading to the religious and tourist town of Mashad, located about 1,000 kilometers (621 miles) northeast of the capital of Tehran, the radio report said. No other details were immediately provided.

Iran has one of the worst road safety records in the world. More than 26,000 people lose their lives in road accidents annually. The toll is blamed on unsafe vehicles, disregard for traffic rules and inadequate emergency services.