Afghanistan:U.S. airstrike killed 3 MSF workers in hospital.

Airstrikes killed three staff workers of medical aid group Doctors Without Borders early Saturday in the Afghan city of Kunduz, the charity said. U.S. forces said they conducted airstrikes in the area.

More than 30 people remained unaccounted for after aerial bombing hit the trauma center several times, the charity said in a statement.

U.S. forces carried out a nearby strike early Saturday "against individuals threatening the force," Army spokesman Col. Brian Tribus said.

The strike "may have resulted in collateral damage to a nearby medical facility," he said in a statement. The military is investigating.

"We do not yet have the final casualty figures, but our medical teams are providing first aid and treating the injured patients and MSF personnel," said Bart Janssens, operations director for the organization also known as Medecins Sans Frontieres.

When the aerial attack occurred, 105 patients and their caretakers were in the hospital. More than 80 MSF international and national staff were present.

The International Committee of the Red Cross condemned the bombing of the hospital.

"Such attacks against health workers and facilities undermine the capacity of humanitarian organizations to assist the Afghan people at a time when they most urgently need it," said Jean-Nicolas Marti, Head of the ICRC delegation in Afghanistan.