The Israeli army on Sunday responded by heavy fire to unarmed pro-Palestinian protesters at the cease-fire line between Syria and Israel, killing 20 people and wounding 325 others, the state-run Syrian TV reported.
The TV said the 20 victims included a child and a woman, and 12 of the injured were in "grave condition."
A group of young Palestinian refugees tried Sunday to cross the barbed wire fences into the Israeli-controlled Majdal Shams, to mark the "Naksa Day", or "setback day", the anniversary of the six- day 1967 Arab-Israeli War, in which Israel seized control of the Golan Heights, the West Bank, eastern Jerusalem, the Gaza Strip and northern Sinai.
Xinhua reporters saw 200 to 300 protesters gathering at the " Shouting Hill" near Majdal Shams, among whom some 40 to 50 were approaching the security fences, waving a Syrian flag and shouting slogans.
The young men carried the Palestinian and Syrian flags and shouted slogans such as "the people want to liberate Palestine."
They also carried banners, one of which read that "our martyears are torches on the road of return."
The Israeli army opened fires as the protesters tried to cross the fences shortly before Sunday noon.
Dozens of ambulances were shuttling to carry the injured to a nearby hospital, according to a Xinhua reporter.
Khaled Abu Susseh, operations director of the Syrian Red Crescent, told Xinhua that "we came here to treat the injured and transfer them to the hospital," adding that "most injuries were caused by gunshot in the face."
However, Israeli media said the army used exact and limited live fire at the legs of the protesters.
The Israeli army spokesman's office told Xinhua that soldiers shot into the air as dozens of protesters kept approaching the fences, despite warnings.
The Israel Radio played an audio segment of Israeli troops with bullhorns warning the protesters in Arabic that they would be shot if they approached the barbed-wire fencing.
Hasan al-Saady, one of the protesters, told Xinhua that "my house is in Jaffa and I want to go there even if I died."
"The Israeli soldiers fear the Palestinians and that's why they open fire before we even get close to them," said another protester.
Israel Channel 2 television reported at noon that several dozen protesters were seen approaching the border fences several kilometers further south at the Kuneitra crossing point where the UN have a force stationed.
The Islamic Hamas movement welcomed in a statement the attempts by Palestinians to break through the borders with Israel, saying it was "an important step towards restoring our rights, mainly the right of return."
It also urged the Palestinians to repeat such kind of attempt.
"What happened today showed the Palestinian people's determination to restore all the national rights topped by the right of return," Maher al-Taher, a senior official of the Popular Front for Liberation of Palestine, told Xinhua by phone, adding that "the Palestinian youths wanted to deliver a message to the world that the occupation will never last and we are not afraid of Israeli tanks and bombs anymore."
The Israeli army and security forces were on high alert Sunday for possible Palestinian attempts to cross the borders with Lebanon, Syria, Jordan, and the Gaza Strip.
The army declared the entire Golan Heights as a closed military area, and the Lebanese army took similar measures along the border with Israel, in order to prevent potential marches.
Some Palestinian groups, however, reportedly canceled planned marches and were expected to hold rallies in refugee camps in Lebanon and Syria instead.
Sunday's unrest, which is the second incursion happened in the usually tightly controlled Syrian side, broke out after activists used Facebook and other websites to call on Palestinians and their supporters in neighboring countries to march on the borders with Israel.
More than 10 protesters were killed on May 15, the Palestinian "Nakba Day", in a similar attempt along the Lebanese and Syrian borders with Israel, as Israeli and Lebanese armies opened fire.
Israel police are on high alert across the country as well, in hopes of heading off any possible disturbances in the territories and along the borders.