KANDAHAR  - Afghan security forces have killed dozens of militants in a military operation aimed at freeing a group of civilian hostages in southern Afghanistan, an army official said on Wednesday.

Masked gunmen kidnapped around 30 passengers from two buses in the southern province of Zabul last week while they were travelling late at night to the capital, Kabul. Eyewitnesses said most passengers belonged to the ethnic Hazara minority, a group that was persecuted by the Taliban during their hard-line rule in the late 1990s. A team of Afghan army, police and intelligence agents had identified several locations where the civilians were being held, but had yet to free any hostages. “The rescue operation is ongoing,” General Abdul Hameed, commander of the 205th Afghan army corps operating in the south of the country, told Reuters. “We have killed 48 insurgents and 21 of them are foreign fighters.”

He identified some militants as local Taliban, but did not indicate the nationalities of the foreign fighters. The hostages were forced to get out of the buses on Feb 23 after producing documents showing they belonged to the Shia group, according to one of the bus company’s managers.

The Taliban have not claimed responsibility for the kidnapping.