JERUSALEM — An Israeli investigation into the killings of 15 Palestinian medics last month in Gaza by Israeli forces said Sunday it found a chain of “professional failures” and a deputy commander has been fired.

The shootings outraged many in the international community, with some calling the killings a war crime. Medical workers have special protection under international humanitarian law. The International Red Cross/Red Crescent called it the deadliest attack on its personnel in eight years.

Israel at first claimed that the medics’ vehicles did not have emergency signals on when troops opened fire but later backtracked. Cellphone video recovered from one medic contradicted Israel’s initial account. Footage shows the ambulances had lights flashing and logos visible as they pulled up to help another ambulance that earlier came under fire.

The military investigation found that the deputy battalion commander acted under the incorrect assumption that all the ambulances belonged to Hamas militants. It said the deputy commander, operating under “poor night visibility,” felt his troops were under threat when the ambulances sped toward their position and medics rushed out to check the victims. The military said the flashing lights were less visible on night-vision drones and goggles.

The ambulances immediately came under a barrage of gunfire that went on for more than five minutes with brief pauses. Minutes later, soldiers opened fire at a U.N. car that stopped at the scene.

Eight Red Crescent personnel, six Civil Defense workers and a U.N. staffer were killed in the shooting before dawn on March 23 by troops conducting operations in Tel al-Sultan, a district of the southern Gaza city of Rafah.