Israeli troops opened fire on Sunday as protesters on Syria's side stormed a ceasefire line on the occupied Golan, killing at least four demonstrators according to Syrian television.
The military said soldiers fired at demonstrators after warning them to back away from the fence which marks the ceasefire line along the Golan Heights.
"Despite numerous warnings, both verbal and later warning shots in the air, dozens of Syrians continue to approach the border and IDF (Israel Defence Forces) forces were left with no choice but to open fire towards the feet of protesters in efforts to deter further actions," a spokesman told AFP.
Syrian state television reported that three people were killed and nine more wounded in the incident, as an AFP photographer saw at least four protesters evacuated with apparent injuries.
The television showed footage of Syrian and Palestinian youths trying to scale the fence as Israeli soldiers on top of a tank opened fire. "Three martyrs have fallen, including a child, and nine others have been wounded," it said.
On the Israeli side, officials from the Golan Heights town of Majdal Shams shouted at the soldiers, calling on them to stop firing.
Meanwhile, the troops used loudspeakers to warn demonstrators in Arabic that "anyone who comes close to the fence will be responsible for their own blood."
Israeli troops opened fire as demonstrators began cutting through the first of two lines of barbed wire set up to try to prevent them from reaching a chain fence along the ceasefire line between the two countries.
Israel forces have been on high alert after activists in the West Bank and Gaza Strip, and in Arab nations bordering the Jewish state called for protesters to march on Israeli checkpoints and border areas.
Sunday's protests, timed to coincide with the 44th anniversary of the Six-Day War, when Israel captured the Golan from Syria, are intended to be a repeat of massive demonstrations last month.
On 15 May, thousands of protesters massed on Israel's borders with Syria and Lebanon, and the Gaza Strip, trying to force their way across on the anniversary of Israel's creation.
Israeli troops opened fire on demonstrators as they stormed the borders from Syria and Lebanon, leaving six dead on the Lebanese side of the border and four dead on the Syrian side.
Activists had called on Palestinians and their supporters to stage similar demonstrations on Sunday, prompting the Israeli military and police to deploy extra forces in West Bank and along all of its borders.
In the Gaza Strip, protesters gathered outside the northern town of Beit Hanun, but Hamas police prevented them from moving further north towards the Erez border crossing with Israel.