The army of Israel opened fire because there where more than 35,000 people protesting at the fence.
The reason why they are protesting is because Israel celebrates their 70-years anniversary which is, looked from the Palestinian side, a catastrophe for the Palestinian people.
Also today is the day that the US will move their embassy from Tel Aviv to Jerusalem. Something the Palestinian people are not happy about. Trumps daughter, Ivanka Trump, is present with husband Jared Kushner. They already arrived this Sunday and already had a visit to Israel PM Benjamin Netanyahu.
The protests, which started in March, where already violent from the start. Before monday there where already 40 deaths reported on the Palestinian side. There are no reports from the Israeli-an side on injured people or deaths.