Ashraf al-Qidra, spokesperson for the health ministry in the besieged enclave, identified the children as Khaled Bassam Mahmoud Abu Saeed, 14; Abdul Hameed Mohammed Abdul Aziz Abu Zaher, 13; and Mohammed Ibrahim Abdullah al-Sutari, 13.
He said ambulances brought their bodies to Al-Aqsa Martyrs Hospital in Deir al-Balah in the central Gaza Strip.
Palestinian news agency Wafa said the Israeli army “reportedly opened fire toward the ambulances and prevented their access” to the scene of the bombing, located northeast of Khan Younis.
In a statement, the Israeli military said its aircraft fired upon three Palestinians who approached the fence and “were apparently involved in placing an improvised explosive device (IED) adjacent” to the fence.
The killings come a day after Palestinian group Islamic Jihad announced an Egypt-brokered ceasefire with Israel.
The declaration came hours after Israel launched air raids hitting more than 80 locations in the Gaza Strip after it said rockets were fired from there into southern Israel.
Egyptian mediators are attempting to negotiate a truce between Hamas, which rules the Gaza Strip, and Israel, and avoid a full-scale war.
For the last seven months, Palestinians in the Gaza Strip have been staging regular demonstrations along the fence with Israel to demand the right to return to their homes from which they were forcibly expelled from in 1948.
They also demand an end to the years-long Israeli-Egyptian blockade of Gaza, which has devastated the coastal enclave’s economy and deprived its more than two million inhabitants of many basic commodities.
Since the rallies began on March 30, more than 200 Palestinians have been killed and thousands more wounded by Israeli forces.