The pre-dawn airstrike killed three members of the resistance movement’s armed wing, the Ezzedine al-Qassam Brigades.
The Brigades, who identified them as “senior commanders” Mohammad Abu Shamala, Raed al-Atar and Mohammad Barhum, vowed to make Israel pay.
“The assassination ... is a big Israeli crime, which will not succeed in breaking our will or weakening our resistance,” spokesman Sami Abu Zuhri said Thursday.
Israel’s Shin Bet internal security agency said Atar and Shamala were among the top five most-wanted Hamas fighters.
Israel’s Minister for Military Affairs Moshe Yaalon hailed their deaths as “a big operational and intelligence achievement,” and warned that Israel would not hesitate to track down the rest of the group’s leaders.
Witnesses said nine missiles blasted the four-story building in Rafah to smithereens, leaving a huge crater.
Four surrounding buildings had their doors and windows blown out and some outer walls destroyed.
The body of Sabah Yunis, a 4-year-old girl, was also pulled from the rubble, emergency services spokesman Ashraf al-Qudra said.
The deadly strikes came 36 hours after Israel tried and failed to assassinate Brigades chief Mohammad Deif, who has topped its most wanted list for more than a decade.
That attack leveled a six-story building in Gaza City, killing two women and three children, among them Deif’s wife, his infant son and 3-year-old daughter, although he escaped unharmed.
Around 27 people were killed in Israeli strikes across Gaza Thursday, day 45 of the bloody conflict.
Others died of wounds, raising the overall death toll to 2,083 Palestinians since July 8.
The UN has identified about 70 percent of them as civilians.
On the Israeli side, 67 people have been killed, 64 of them soldiers. One civilian was severely wounded when a mortar round hit an area not far from the Gaza border Thursday, the army said.
In the 48 hours since the truce broke down, Gaza fighters have launched 283 rockets, 219 of which struck Israel and another 44 of which were shot down, the army said.
BA/BA