Israeli soldiers shoot tear gas from the Israeli side of the border with Gaza, as Palestinians protest on the Gaza side, March 30, 2018. Photo: Reuters / Amir Cohen.

At least 12 Palestinians were killed by Israeli security forces confronting one of the largest demonstrations along the Israel-Gaza border in recent years, Palestinian medical officials said.

The Israeli military said that its troops had used “riot dispersal means and firing towards main instigators” and that some of the rioters were “rolling burning tires and hurling stones” at the border fence and at soldiers.

Live fire was used only against people trying to sabotage the border security fence and at least two of the dead were Hamas operatives, according to an Israeli military official.

Palestinian health officials said Israeli forces used mostly gunfire against the protesters, in addition to tear gas and rubber bullets. Witnesses said the military had used a drone in at least one location to drop tear gas.

The Palestinian protest marked “Land Day,” an annual commemoration of the deaths of six Arab citizens of Israel killed by Israeli security forces during demonstrations over government land confiscations in northern Israel in 1976.

The demonstrators demanded that Palestinian refugees be allowed the right of return to towns and villages which their families fled from, or were driven out of, when the State of Israel was created in 1948.

Tensions ran high at the start of the long-planned tent protest that began on Good Friday and the start of the Jewish Passover and is scheduled to last for six weeks. Israeli security forces are customarily on a state of high alert during holidays, with tighter restrictions on movement of Palestinians.

There were also small protests in the West Bank. But the main focus was Gaza, from which Israeli soldiers and settlers withdrew in 2005 after 38 years. The Gaza Strip is now ruled by the Islamist terrorist group Hamas and blockaded by Israel and Egypt.

Gaza officials said tens of thousands of protesters gathered at five locations along the 65-kilometer (40-mile) border with Israel. The Israeli military estimate was 30,000.

Families brought their children to camps just a few hundred meters from the border fence, with football fields marked out in the sand, and scout bands playing.

But as the day wore on, hundreds of Palestinian youths ignored calls from the organizers and the Israeli military to stay away from the frontier, where Israeli soldiers across the border kept watch.

In a statement, the Israeli military accused Hamas of “cynically exploiting women and children, sending them to the security fence and endangering their lives.”

The military said that more than 100 army sharpshooters had been deployed in the area and earth-moving vehicles piled up dirt mounds to stop any attempt to breach the barrier.

Maj. Gen. Eyal Zamir, head of the IDF’s Southern Command, said his forces had identified “attempts to carry out terror attacks under the camouflage of riots.”

Hamas, which seeks Israel‘s destruction, had earlier urged protesters to adhere to the “peaceful nature” of the protest.

In Gaza, the protest was dubbed “The March of Return” and some of the tents bore names of the refugees’ original villages in what is now Israel, written in Arabic and Hebrew alike.

Israel has long ruled out any right of return, fearing an influx of Arabs that would wipe out its Jewish majority. It argues that refugees should resettle in a future state the Palestinians seek in the West Bank and Gaza. Peace talks to that end have been frozen since 2014.

The protest is scheduled to culminate on May 15, the day Palestinians commemorate what they call the “Nakba,” or “Catastrophe” — i.e. Israel’s establishment.

The protest organizers include Hamas and representatives of other Palestinian factions.

Hamas leader Ismail Haniyeh spoke at one tent encampment on Friday, saying that Gazans were demanding a “return to Palestine, all of Palestine. No concessions and no recognition of the Zionist entity (Israel) in any inch of the land.”