KABUL: A magnetic bomb attached to a minivan exploded in a heavily Shia area of the Afghan capital Kabul on Saturday, causing an unknown number of casualties, a Taliban official and local residents said.

The Taliban official, who declined to be named, said six people had been killed and at least seven wounded in the blast in the Dasht-e-Barchi area of western Kabul, the latest in a series of attacks across Afghanistan in recent weeks.

There was no confirmation of casualty numbers and no immediate claim of responsibility. The area is heavily populated by Shia Hazaras who have been the target of repeated attacks by Islamic State militants.

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Zabihullah Mujahid, the Taliban's main spokesman, said a fire had broken out in the Dasht-e-Barchi area of western Kabul, killing at least one civilian and injuring two others. An investigation was underway, he said in a tweet.

A local man who gave his name as Ismael, said he had reached the area a few minutes after the explosion, which occurred a day after an attack on a Sunni mosque in eastern Afghanistan.

"When I arrived, I saw the big flames," he said. "It was a mini van which was targeted by a sticky bomb."

He said a friend who had helped carried wounded to a nearby hospital said at least three or four people had been killed.

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Images shared on social media showed flames and a thick cloud of black smoke spiralling into the sky. At least two people suffered serious burn injuries, according to a director of a nearby hospital that specializes in burn cases.