A war of words erupted on Twitter Friday between the UN's Mideast envoy and the former spokesman for the Israeli military over the killing of a 15-year-old Palestinian during protests near the Gaza border. The teenager was standing with a group around 100-150 meters from the border when he was shot, Palestinian medical sources said.

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The Twitter confrontation began with an unusually fiery tweet by UN Special Coordinator for the Middle East Peace Process Nickolay Mladenov, who condemned the teenager's killing, which Gaza's Health Ministry said was a result of Israeli live fire. Mladenov described the incident as outrageous and said "the killing of a child" in Gaza "fuels anger and breeds more killing." He added that the incident must be investigated.

Open gallery view Mohammed Ayoub, 15, who was killed during protests near the Gaza border.

Peter Lerner, a crisis communications consultant who served for 25 years in the IDF as a spokesperson and liaison officer, tweeted that Mladenov's comments were "unhelpful" and suggested steps for Mladenov to take: "1. Please go to Gaza, engage Hamas and get them to stop sending people to the fence. 2. Report to the UN your efforts (not tweets) to restore calm. 3. Stop Palestinian incitement and organized riots at the border."

Lerner then responded to another tweet by saying that "the tweet from THE most senior UN official does nothing to prevent the next death. Here's another idea – get everybody on the UN payroll in Gaza to make a human chain at a safe distance and prevent people from going to the fence."

Mladenov replied tersely: "Here's another idea. Stop shooting children."

In a tweet later that night, Israeli Ambassador to the UN Danny Danon accused Hamas of instigating violence, noting that protesters used firebombs and tried to breach the border into Israel. "I call on all @UN officials to condemn Hamas for encouraging violence & for despicably exploiting women & children by placing them in harm’s way," Dannon wrote.

President Trump's special envoy to the Mideast negotiations, Jason Greenblatt, tweeted Friday overnight that "A full investigation by Israel of Mohammed Ayoub’s death is underway so that we will be able to understand what happened." Greenblatt concluded by calling all sides to avoid causing more suffering by responding to Ayoub's death.

Mladenov, a citizen of Bulgaria, was appointed to his role in 2015. He previously served as the UN's special representative for Iraq and as Bulgaria's foreign and defense minister. Before that, he was a member of the European Parliament and of Bulgaria's parliament.

Open gallery view Israeli soldiers are seen during protests along Israel Gaza border, Friday, April 20, 2018. Credit: Tsafrir Abayov/AP

The killing of 15-year-old Mohammed Ayoub was among four reported by the Healthy Ministry in Gaza on Friday as thousands of Gazans protested along the border in the fourth consecutive week of the "March of Return." The ministry said a total of 156 prosters were wounded by Israeli live fire.

The march is part of a month-and-a-half-long protest organized by Hamas near the border fence. The committee organizing the protests said the marches will not stop before May 15, at the very least, the day the Palestinians commemorate the Nakba, which is based on the date in the Gregorian calendar for the establishment of the State of Israel.

According to the IDF, protesters have tried numerous times during past marches to damage the border fence and cross it, and have thrown explosive devices and firebombs at Israel forces.

In the three weekends of protest preceding Friday, 34 Palestinians were reportedly killed by IDF fire, and the bodies of two of them who tried to attack an IDF position are still being held by Israel.