The seven aid workers had arrived in northern Gaza earlier on Monday to help deliver more than 100 tons of food aid, according to World Central Kitchen. Their trucks left around 9 p.m. and headed south for the group’s warehouse, according to the Israeli military.

Along the coastal road, the trucks met with cars who joined their convoy, according to the military. Shortly after, a gunman appeared to fire a single round from the roof of one of the trucks, according to Maj. Gen. Yoav Har-Even, a reserve officer who oversees the military’s investigations into potential cases of wartime misconduct.

The drone operator and his commanding officers were unaware that the cars were part of the approved humanitarian convoy and wrongly assumed they were carrying armed Palestinians, the Israeli officials said.

Asked why the soldiers were out of the loop, General Har-Even said that certain officers had not seen the coordination documentation. “No excuses,” Gen. Har-Even said, describing the communications failure.

After the convoy arrived at the warehouse, Israeli drone footage captured what officials said were believed to be more gunmen at the scene. The Israeli military screened videos for reporters at the briefing on Thursday. The New York Times could not independently verify the military’s video.

The officers were convinced that the scene they had witnessed resembled what they said were previous attempts by Hamas militants to seize humanitarian aid in Gaza, the officials said. Basem Naim, a Hamas spokesman, denied that Hamas stole aid, calling the accusation “Israeli propaganda.”

The cars then left the warehouse — three cars went south and one went north, the military officials said. Before they left, a drone operator spotted what he believed — wrongly, General Har-Even said — was a figure bearing a weapon entering one of the three southbound cars.

Within four minutes, at least one Israeli drone struck each of the three vehicles in the convoy as they traveled south one behind the other, killing all seven passengers, the Israeli officials said. Israeli officers fired on the first car without “enough to say this is a legitimate target,” said Benny Gal, one of the Israeli generals who briefed reporters.

Some aid workers in the first vehicle struck fled to the next vehicle for protection, the officials said. That vehicle was hit, too.

The soldiers’ decision to fire on the second and third car, assuming wrongly that they were also harboring militants, failed to meet the Israeli military’s open-fire protocols, the officials said. The Israeli military’s rules of engagement are classified, making it difficult to know what the standard for using deadly force was on Monday night. But General Har-Even indicated the attack categorically broke them.

“This was against the rules of engagement,” he said.