The Israeli military has said it fired only at "instigators" involved in attacks on soldiers or the border fence. It had no immediate comment.
Murtaga worked for Ain media, a local TV production company that has done projects, including aerial drone video, for foreign media. He was not affiliated with any militant group.
The UN human rights office said it has indications that Israeli forces used "excessive force" against protesters last week, when 15 Palestinians were killed or later died of wounds sustained near the border.
An Israeli military spokesman defended the rules of engagement.
Yesterday's large crowds suggested that Hamas, the Islamic militant group that has ruled Gaza since a 2007 takeover, might be able to keep the momentum going in the next few weeks.
Hamas has called for a series of protests until May 15, the anniversary of Israel's founding when Palestinians commemorate their mass uprooting during the 1948 war over Israel's creation.
Israel has alleged that Hamas is using the mass marches as a cover for attacking the border fence, and has vowed to prevent a breach at all costs. The military said yesterday protesters hurled several explosive devices and firebombs, using the thick plumes of smoke from burning tyres as a cover, and that several attempts to cross the fence were thwarted.
The mass protests are perhaps Hamas' last chance to break a border blockade enforced by Israel and Egypt since 2007, without having to succumb to demands that it disarm.
The blockade has made it increasingly difficult for Hamas to govern. It has devastated Gaza's economy, making it virtually impossible for people to enter and exit the territory, and left residents with just a few hours of electricity a day.
For a second week in a row, the United States blocked a UN Security Council statement supporting the right of Palestinians to demonstrate peacefully and endorsing Guterres' call for an independent investigation into the Gaza protests.
