At least 21 people died and 20 others were injured after a bus and a fuel tanker collided in central Iran, officials say.
The accident occurred late on September 17 on a motorway between the cities of Kashan and Natanz, more than 200 kilometers south of the capital, Tehran.
"The tanker swerved to the side, hitting the bus and causing an explosion and fire," said traffic police commander General Mohammad-Hossein Hamidi.
State television broadcast footage of firefighters battling the blaze as rescue teams rushed to take the wounded to hospitals.
"The flames started at the front of the bus as diesel from the tanker poured in," an unnamed survivor said from his hospital bed, adding that he managed to escape through a window of the bus.
The bus was carrying passengers from Tehran to the city of Kerman, some 1,000 kilometers to the southeast, when the collision occurred.
Many Iranians are traveling this week as Ashura, the holiest celebration in the Shi'ite religious calendar, gets under way.
Iran has one of the world's worst traffic safety records, with Health Ministry officials reporting around 16,300 killed during the Iranian year that ended in March.
Widespread disregard for traffic laws, unsafe vehicles, poor quality of the road network, and inadequate emergency services are among the main causes.