Several videos circulating on social media purport to show Palestinian protesters being shot in the back or while praying by Israeli snipers.In one of the videos, a demonstrator - identified by relatives as 19-year-old Abdelfattah Abdelnabi - is shot in the back while running away from the border separating the Gaza Strip and Israel.The footage shows Abdelnabi and another Palestinian being just a few metres away from a small group of unarmed protesters. A loud shot rings out and Abdelnabi drops to the floor.According to the Palestinian health ministry, Abdelnabi died from his wounds.More than 100 snipers were deployed to the border for the planned demonstrations, according to Israeli media.In another video, a worshipper was shot in his right leg while he was performing Asr, the afternoon prayer, near an Israeli border fence.The group of Muslims praying next to him stopped their communal prayer before rushing to seek cover.In a third video, an unarmed Palestinian girl was shot as she waved a Palestinian flag near the border. It was unclear what injuries she sustained.Al Jazeera could not independently verify the videos. 'Right of return'At least 17 Palestinians were killed and more than 1,400 others wounded on Friday after Israeli forces fired live ammunition, tear gas and rubber-coated bullets at protesting Palestinians.Friday's demonstrations commemorated Land Day, which took place on March 30, 1976, when six unarmed Palestinian citizens of Israel were killed by Israeli forces during protests against the Israeli government's decision to expropriate massive tracts of Palestinian-owned land.Organisers of the protest, dubbed the Great Return March, said the main message of their six-week demonstration was to call for the right of return for Palestinian refugees.Abdelnabi's brother, Alaa, said his sibling "went to the march to see his country on the other side, to see the return of our people to their lands - but they responded with violence."He had no weapons, and yet they attacked him with violence. This is the price we have to pay to return to our lands," Alaa Abdelnabi told Al Jazeera.Adalah, a legal centre for Palestinian rights in Israel, condemned the Israeli army's use of force, calling it a violation of international law. "Live gunfire on unarmed civilians constitutes a brutal violation of the international legal obligation to distinguish between civilians and combatants," the group said in a statement.It also said that it would launch an investigation to "demand that those found responsible for the killings be brought to justice". The protest is due to end on May 15, the day Palestinians call the "Nakba" or "Catastrophe", marking the displacement of hundreds of thousands of Palestinians in the conflict surrounding the creation of Israel in 1948.Palestinians have long demanded that as many as five million direct descendants of the original Palestinian refugees be given the right to return to their ancestral homes.Israel rules this out, arguing that the return of Palestinians to what is now Israel would outnumber its Jewish majority.