The IDF special forces unit killed eight Palestinian Red Crescent personnel, six emergency rescue workers and a United Nations employee in three separate predawn attacks at the same location south of Rafah, then buried the 15 aid workers in a mass grave along with their crushed emergency vehicles.

Firing on the first medical team and then the ambulance crews that came to find them an hour later “resulted from an operational misunderstanding by the troops,” the report said, while killing the U.N. worker was “a breach of orders.”

Israel’s military advocate general was investigating the incident and could pursue criminal charges, but “there are no outside investigations of the killings underway,” the AP said. The IDF has “killed more than 150 emergency responders” and “well over 1,000 health workers,” according to the U.N., and it “rarely investigates such incidents.”