MEXICO CITY – The Mexican army acknowledged for the first time Friday that some of its soldiers have been killed by bomb-dropping drones operated by drug cartels.

Defense Secretary Gen. Luis Cresencio Sandoval did not provide exact figures on the number of casualties suffered in the attacks, almost all of which occurred in the western state of Michoacan.

“Our personnel have suffered wounds, and some of our troops have even died” in the attacks, Sandoval said. The army had previously acknowledged that soldiers had been wounded in Michoacan by improvised explosive devices, or IEDs.