The soldiers, all members of a combat engineering unit, were in an armored carrier that was hit by an explosion that detonated engineering materials being carried on the vehicle, apparently in contravention of standard practice, the military said. It said the early morning incident, in the Tel al-Sultan area in the west of Rafah, was being investigated.
The armed wing of the Palestinian militant group Hamas said the vehicle had been trapped in a prepared minefield that set off the explosion.
Israeli tanks advanced in Tel al-Sultan and shells landed in the coastal area, where thousands of Palestinians, many of them displaced several times already, have sought refuge.
Despite growing international pressure for a ceasefire, an agreement to halt the fighting still appears distant, more than eight months since the start of the war in October, with the near-daily cross-border exchanges of fire with Hezbollah militia fighters in southern Lebanon intensifying.