Israeli warplanes struck a target in Rafah early Wednesday, killing Muhammad al-Sheikh, 32, a member of the PRC's military wing the Nasser Saladin Brigades.
One other person was also injured in the attack.
Israel's army said it was targeting a launching squad which moments earlier had fired a rocket at southern Israel.
At midnight, an airstrike on Beit Lahiya in Gaza's north killed Ismail al-Tille, a member of Hamas' al-Qassam Brigades, and injured three others, Gaza Health Ministry spokesman Ashraf al-Qidra told Ma'an.
Another overnight strike in an area northwest of Beit Lahiya killed Loai Abed al-Hakeen Abu Jarad, 24, and Yousef Abu Jalhoum, al-Qidra said. One other person was seriously wounded.
Israel's army said it targeted a squad in the northern Gaza Strip "during its final preparations to fire rockets towards southern Israel."
Later it said aircraft targeted a "terror tunnel" and "terror activity sites."
A statement said over 65 rockets fired from Gaza targeted areas in southern Israel since midnight.
"The IDF will not tolerate any attempt to harm Israeli civilians, and will operate against anyone who uses terror against the State of Israel. The Hamas terror organization is solely responsible for any terrorist activity emanating from the Gaza Strip," the statement said.
Hamas officials also reported Israeli tanks firing into Gaza. A military spokesman confirmed that report.
Gaza's ministry of education said six schools have been evacuated in Khan Younis due to Israeli airstrikes in the area.
Late on Tuesday, an Israeli airstrike killed one man and injured three others after Israel's army said six rockets fired from the Gaza Strip landed across the border, a medical official said.
The attack came hours after Popular Front for the Liberation of Palestine fighters claimed responsibility for an attack that wounded an Israeli soldier on the Gaza border. The Abu Ali Mustafa Brigades said it was responsible for a bomb that went off beside an army patrol east of Khan Younis.
Israeli Prime Minister Benjamin Netanyahu had said Israel would deliver a strong response to the attack. "We will fight and we will hit them very, very hard," Netanyahu said.
An Israeli army spokesman said that over 60 rockets have been fired at Israel since late Tuesday, injuring three foreign workers in Israel's southern Eshkol region.
The airstrikes followed a historic visit by the Emir of Qatar, which broke the isolation of the Hamas leadership in Gaza.
Thousands lined the streets in Gaza to welcome the Qatari emir, who was the first head of state to visit the Hamas-run enclave since 1999.
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