A probe has been launched to "find the perpetrators", Taliban interior ministry spokesman Qari Sayed Khosti told AFP, adding two soldiers were wounded after "a grenade was thrown at a mujahideen vehicle in Deh Mazang".

Another official said: "Our initial information shows four school students wounded."

The explosion happened just before 8 am (0330 GMT) during rush hour in the Deh Mazang district in the west of Kabul, a witness told AFP.

"I was on my way to work, it was 7.55 am and I heard this very big explosion on the road. I managed to escape," said Amin Amani.

"I saw a lot of smoke in the mirror of the car and I saw people running," the 35-year-old translator said.

Images shared on social media showed plumes of smoke and dust rising into the air on the streets of the capital.

Broken glass could be seen at the scene of the blast as security forces stood guard, ushering bystanders away as traffic resumed on the surrounding roads