Nineteen people – including 12 staff and 7 patients – were killed today when an airstrike hit a Doctors Without Borders hospital in Kunduz, Afghanistan. And it appears that this may be a terrible incidence of “friendly fire,” as preliminary reports indicate that this was a US-led NATO airstrike.

The commander of U.S. forces in Afghanistan says the military is opening an investigation into the deadly bombing of a Doctors Without Borders facility in the northern Afghan city of Kunduz.

“While we work to thoroughly examine the incident and determine what happened, my thoughts and prayers are with those affected,” said Gen. John F. Campbell in a statement.

U.S. forces conducted an airstrike “in the vicinity” of the hospital around 2:15 a.m. local time, targeting insurgents who were firing upon U.S. service members “advising and assisting” Afghan security forces, the statement said.

The charity reports that the hospital was repeatedly bombed at approximately 15-minute intervals between 2:08 a.m. and 3:15 a.m. Saturday morning.

The Taliban attacked Kunduz this last Monday, according to reports.