International medical charity Doctors Without Borders has withdrawn from the northern Afghan city of Kunduz after a deadly airstrike destroyed its hospital.

Kate Stegeman, the group's communications manager, said Sunday some staff are working in other health facilities in the city, where troops have been battling Taliban insurgents.

Investigations are continuing into the bombing of the hospital on Saturday, which killed at least 19 people, including 12 of the group's staffers.

The group blames a U.S. airstrike, though Afghan officials have said helicopter gunships returned fire from Taliban fighters who were hiding in the facility.

The Taliban seized Kunduz last Monday but have since withdrawn from much of the city in the face of a government counterattack. Sporadic battles continue as troops attempt to clear remaining pockets of militants.