Dozens of oil and gas tankers carrying millions of dollars' worth of fuel caught fire on Saturday, creating an inferno at Afghanistan's biggest trade crossing with Iran, officials said.
The blaze broke out in the early afternoon at Islam Qala port, 120 kilometres (75 miles) from the western city of Herat, engulfing the tankers that were 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 kilometre 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."
At least 17 people have been taken to hospital, some of them with serious burns, said Ibrahim Mohammadi, head of the Herat ambulance service.
Jailani Farhad, the spokesman for the governor of Herat province, said dozens of tankers were ablaze.
"We don't have the required facilities to contain it, so through the foreign ministry, we have asked the government of Iran to help us contain the fire," he said.
The cause of the fire was unknown, he added.
Videos posted on social media show towering flames and huge clouds of thick black smoke billowing into the sky.
Around 60 percent of Herat province was without power as a result of the fire, Afghan energy company DABS said.
Islam Qala is one of the major ports in Afghanistan, through which most official trade with Iran is conducted.
Afghanistan has received waivers from Washington allowing it to import oil and gas from Iran despite US sanctions.
Iran foreign ministry spokesman Saeed Khatibzadeh said the border "was held open for trucks, cars and people running from the fire" towards Iran.
He added that authorities from both countries were helping to tackle the blaze.
Taking advantage of the situation, Taliban insurgents attacked a nearby security post after the blaze broke out, Farhad added.
Afghanistan has been hit by a surge in violence despite peace talks that started in September between the Taliban and the Afghan government, which have so far failed to achieve a breakthrough.
The rise in violence has led US President Joe Biden's administration to launch a review of a deal signed between Washington and the Taliban last year that paved the way for the withdrawal of all American troops in the coming months.