A video that captured their deaths — from a store’s surveillance footage — was obtained by Defense for Children International (DCI), a Geneva-based rights group, on May 17. A spokesman for DCI said that the boys did not appear to be posing any threat to soldiers at the time of their deaths.

“In the video there is a lull in the violence, and it’s at that time when both teens were not posing a direct and immediate threat to life that they were shot,” Ivan Karakashian, advocacy unit coordinator for DCI-Palestine, said. “According to the Israeli Defense Forces [IDF] rules of engagement, you can’t use live ammunition on protesters if they’re not posing a mortal danger to soldiers or others.

“The killings appear to be unlawful,” he added.

The U.S. on Tuesday called for an inquiry into the shooting.

"We look to the government of Israel to conduct a prompt and transparent investigation to determine the facts surrounding this incident, including whether or not the use of force was proportional to the threat posed by the demonstrators," Jen Psaki, spokeswoman for the State Department, said.

The IDF's North American media office said in an emailed statement that “a preliminary investigation determined that live fire was not used by security forces. This incident remains under investigation.”

The IDF called Thursday’s demonstration “violent” and said Palestinians had burned tires and thrown rocks, so security forces used riot dispersal means to restore calm.

Karakashian said DCI does not deny there were violent clashes at points throughout the protest, with Palestinian youths throwing stones at heavily armed Israeli soldiers in riot gear, but said the shootings occurred during a period of calm.

The owner of the store whose footage captured the shootings said in the video released by DCI that one of the youths was shot “when nothing was going on. The army had fired plenty of tear gas canisters, and the youth had retreated back.”

Then, he said, “I heard live ammunition being fired. Four shots, to be exact. At the moment of the killings, nothing was going on and no stone throwing was taking place.”