The three men, all aged 19, were apparently hit by Israeli tank fire in the Palestinian village of Guhr al-Dik near the settlement of Netzarim late on Sunday, the officials said.
An Israeli military source confirmed that forces fired at "three suspicious figures" spotted approaching a road leading out of Netzarim, a road Israel has declared off limits to Palestinians for fear its convoys could come under attack.
The bodies were recovered on Monday by Palestinian medics, who said the men were unarmed.
Meanwhile, a Palestinian seriously wounded last month in an Israeli air strike on a Gaza city house died of his injuries on Monday, Palestinian medical sources said.
Adam Abid Hashim, 30, lived in the house next door to the building targeted in the raid which killed two Islamic Jihad activists on 16 March.
His death brings the overall toll since the September 2000 start of the Palestinian uprising to 3894, including 2927 Palestinians and 898 Israelis, according to an AFP tally.
Meanwhile, a Palestinian cabinet meeting scheduled to take place on Monday was postponed due to Israel's closure of the occupied territories, Palestinian Foreign Minister Nabil Shaath said.
Several ministers, mainly from the Gaza Strip, were unable to travel due to stepped up restrictions imposed by Israel for the Jewish holiday of Passover, Shaath told Palestinian radio.