The Hamas interior ministry in Gaza accused Egyptian forces on Saturday of "executing" a mentally-ill Palestinian who had waded through the sea into Egypt's territory.
Video broadcast by Al-Jazeera network and Gaza media outlets showed the young man walking in the sea, naked, and then crossing through a wire fence into Egyptian territory before he is fired at several times while still in the water.
WARNING - GRAPHIC VIDEO:
Another person on the beach appears to signal to security forces at a watchtower to stop shooting and the man's body is seen floating in the water and then washed up on shore.
"The shocking images aired by media outlets showing the death of the mentally disturbed young man by the Egyptian military mere meters from the border at Rafah testifies to the level of cruelty of those who carried it out and show that this was a cold-blooded execution," said the Hamas interior ministry in Gaza.
"This is a reprehensible act that goes against all humanitarian laws and conventions," read the ministry's statement, which called for Egyptian authorities to open an investigation and prosecute military personnel who were involved in the incident. According to Hamas, the man's body was still in Egyptian custody.
Palestinians demanded answers on social media, with some users uploaded images of the man alongside an article from the Egyptian press reporting that the military had returned four Israeli soldiers who accidentally entered Egyptian territory near Taba Border Crossing.
The incident and Hamas's response are another chapter in the ongoing difficult relations between the terrorist group and Egyptian President Abdel-Fattah al-Sisi, which have been tense in light of the president's failure to arrange for the opening of Rafah Border Crossing and terror attacks on troops by the local ISIS affiliate.
Reuters contributed to this report.