KABUL — Six employees of the International Committee of the Red Cross were killed and two others were missing after an attack in northern Afghanistan on Wednesday that officials attributed to affiliates of the Islamic State group.

“This is a despicable act. Nothing can justify the murder of our colleagues and dear friends,’’ said the head of the Red Cross delegation in Afghanistan, Monica Zanarelli. “At this point, it’s premature for us to determine the impact of this appalling incident on our operations in Afghanistan.’’

The Taliban, who still inflict the largest share of violence in the 15-year war that has escalated in recent years, quickly denied that they were behind the attack.

The Red Cross has a 30-year history of helping war victims in Afghanistan, providing crucial medical aid to areas near the battlefield. The insurgency also relies on Red Cross volunteers to retrieve the bodies of their dead in large parts of the country and to help their detainees communicate with their families.

But in a recent report, the Red Cross expressed concerns about “the shrinking access of humanitarian aid workers in numerous parts of the country’’ because of the intensifying violence.

The governor of Jowzjan province, Lutfullah Azizi, blamed Islamic State group affiliates for the attack.

Azizi said the Red Cross had begun a mission to distribute livestock material in Qosh Tepa area of Jowzjan province, where the attack happened.

New York Times