TEHRAN, July 11 (Xinhua) -- At least 13 people were killed after a fuel tanker crashed into a passenger bus in Iran's western city of Sanandaj on Wednesday, Tasnim news agency reported.

The passenger bus bound for the capital Tehran departed from the bus terminal of Sanandaj, capital of the western province of Kurdistan, minutes after midnight, Tasnim said.

When the bus pulled over to take in more passengers, a fuel tanker rammed it from behind, causing a huge explosion that burned not only the bus and the truck, but three other vehicles in the vicinity.

The 13 killed in the explosion are 12 bus passengers and the truck driver.

The governor of Kurdistan Province declared three days of public mourning after the tragic accident.