Dozens of oil and gas tankers caught fire on Saturday, creating an inferno at Afghanistan's biggest trade crossing with Iran, officials said.

At least 17 people have been taken to hospitals, some of them with serious burns, according to AFP citing a local ambulance service official. 

The blaze broke out in the early afternoon at Islam Qala port, 120 kilometers from the western city of Herat, engulfing the tankers that parked nearby after crossing the border.

"There were between 200 and 300 fuel tankers there and we managed to save some, but most have been engulfed and the fire is so huge that nobody can get to within even a kilometer of it," said Younus Qazi Zada, head of the Herat Chamber of Commerce. "The initial estimate is of millions of dollars of losses, but we have to wait until the fire is extinguished for a proper assessment of damage."

Videos posted on social media showed towering flames and huge clouds of thick black smoke billowing into the sky. 

The cause of the fire was unknown and the fire has not been put out.

Iran has offered help to contain the blaze. 

"The first step was taken immediately to coordinate the delivery of necessary items to the people and vehicles affected in the fire area," spokesman of Iranian Foreign Ministry Saeed Khatibzadeh said.

The border was kept open for trucks, cars and people fleeing to escape the fire, the official added.

Islam Qala is the biggest dry port that links landlocked Afghanistan to Iran. 

(With input from Xinhua, AFP)