The Baloch Liberation Army (BLA), a separatist insurgent group from the Pakistani south-western province of Balochistan, claimed responsibility for the attack in a message on Twitter.
Khan said Pakistan’s intelligence agencies had successfully preempted at least four major attacks in the country, two of which targeted Islamabad — but he said it was not possible to stop all such attacks.
The gunmen carried a heavy supply of arms and equipment and security officials believe they planned to storm the stock exchange building and take hostages.
Khan termed their failure to do so and the rapid response by security forces, as a “big victory”.
Separatists have been fighting for years in Balochistan, complaining its mineral wealth is unfairly exploited by Pakistan’s richer, more powerful provinces. Balochistan is the site of several projects linked to China’s Belt and Road initiative.
Pakistan has regularly blamed India for supporting Baloch separatists – a charge Delhi has continuously denied.
The BLA also took responsibility for an attack on the Chinese consulate in Karachi in 2018.