BERLIN, Germany (CNN) -- The German chancellor on Sunday called for a quick and thorough investigation into a NATO airstrike in Afghanistan that killed at least 90 people.
A victim of an ISAF airstrike on a hijacked oil tanker is carried into the Kunduz hospital on Friday.
The German commander in the area called in the airstrike Friday in the northern Kunduz province. It happened as Afghans tried to siphon fuel from two tankers hijacked by the Taliban a day earlier.
"Regarding the Kunduz incident, I would first like to clarify that the German government and I personally want to see a NATO investigative team swiftly put together that will carry out a thorough and quick explanation of what took place and whether there were civilians killed," Chancellor Angela Merkel told reporters.
"If there have been civilians among the victims, I will, of course, deeply regret this."
The total death toll has varied depending on the source, but local Afghan officials have said at least half of those killed were civilians.
The Taliban gave villagers the go-ahead to drain the tankers after they became stuck in the mud when the militants tried to drive them through the Kunduz River.
The military believed there were no civilians near the trucks at the time of the attack, ISAF Capt. Elizabeth Mathias said Friday. NATO learned afterward that was not the case.
After touring the site of the massive explosion, Gen. Stanley McChrystal, the top U.S. commander in Afghanistan, said he was convinced that civilians were among those wounded.
"It's important to me that we be as honest with the Afghan people and with people around the world as possible," he said. See images of the strike aftermath »
"Of course, you don't know all the facts until an investigation's complete," he added. "But from what I have seen today in going to the hospital, it's clear to me that there were some civilians that were harmed at that site."
An investigation is under way by NATO and Afghan investigators.