At least 20 people were killed and 10 others were injured in a car accident on a road linking capital city of Tehran to Iran's religious city of Qom on Sunday, state IRIB TV reported.The accident happened after several cars collided, a traffic police official said, adding that the investigation of the cause of the accident is underway.All the victims of the accident are foreigners, mostly from Afghanistan, the unnamed official was quoted as saying.Official figures show that more than 20,000 people died and 200,000 others were wounded in traffic accidents annually in Iran.Inexperienced drivers and low-efficiency of the cars and the roads are blamed for causing the accidents.