KABUL, Afghanistan — With an initial military assessment confirming civilian casualties in the bombing of a Doctors Without Borders hospital in Kunduz by an American warplane, Gen. John F. Campbell, the American commander in Afghanistan, has appointed a two-star general from another command to conduct an independent investigation, his office said in a statement on Saturday.

The announcement came as the death toll in the bombing, one of the worst episodes of civilian casualties in the Afghan war, rose once again, three weeks after the AC-130 gunship repeatedly bombed the trauma center in Kunduz after fighting the Taliban, who had overrun the city. Doctors Without Borders, also known by its French name, Médecins Sans Frontières, said the casualty figures now stood at 23 staff members and patients killed and three others missing who are presumed dead.

Officials are trying to determine the identities of seven unrecognizable bodies found in the wreck of the hospital, all of whom have now been buried, the organization said in a statement on Saturday. The three missing people could be among them.

A spokesman for General Campbell, Brig. Gen. Wilson Shoffner, said an assessment team had “determined that the reports of civilian casualties were credible.” The investigation, which will be conducted by three senior officers outside General Campbell’s command, will be led by Maj. Gen. William B. Hickman and supported by two brigadier generals.