An Israeli father escorting the hike, one of two carrying a gun, fired into the crowd to break it up, killing a Palestinian farmer.
Israeli media reported that the Israeli army fired the shells on an Islamic Hamas movement military post east of al-Mughazi Refugee camp in central Gaza Strip, in response to earlier rockets firing from Gaza into southern Israel.
At around 6:30 pm sirens sounded in the Shaar Hanegev Regional Council in the northwestern Negev.
The violence comes the day after President Donald Trump said he recognized Jerusalem as the capital of Israel.
No terrorist group immediately took responsibility for the attack.
Polish ruling party replaces PM ahead of elections
Polish Prime Minister Beata Szydlo has resigned, hours after surviving an opposition no-confidence motion. Mazurek added that Szydlo had tendered her resignation to the PiS political committee.
Hamas' leader Ismail Haniyeh told Palestinians to rise against Israel, saying Trump's decision declares war against Palestine.
On Wednesday, Trump announced the relocation of the US embassy in Israel from Tel Aviv to Jerusalem - a move which drew numerous negative reactions from Muslim communities around the world.
Nevertheless, IDF tanks and warplanes bombed two Hamas military positions in Gaza in retaliation.
Trump also said the United States would move its embassy from Tel Aviv to Jerusalem, though he set no timetable for that. "Jerusalem is being kidnapped and ripped from us".