An Israeli air strike on a house in Gaza has killed three senior Hamas military commanders, militants say.
Mohammed Abu Shamala, Mohammed Barhoum and Raed al-Attar died in the attack near the southern town of Rafah, which Gaza officials said killed at least 10.
An Israeli was severely injured as rockets were fired into Israel on Thursday, the army said.
Hostilities between the two sides resumed after talks on a long-term ceasefire deal collapsed on Tuesday.
Israel has vowed to pursue its campaign until "full security" is achieved.
Six weeks of fierce fighting have left at least 2,138 people dead, according to officials. All but 67 of the dead are Palestinians, with most of them said to be civilians.
In other developments:
- The Israeli air force attacked and "hit" six Islamic Jihad activists reportedly poised to fire rockets at Israel from northern Gaza
- An Israeli air strike killed four Palestinians as they were burying relatives killed earlier at a graveyard in Gaza City, medics told AFP news agency
- At least six Palestinians, four of them children, were killed in Israeli attacks overnight in the northern town of Beit Lahiya and in Gaza City, AFP reports
'Missile after missile'
Israel's strike on Rafah demolished a four-storey building.
Local man Hamza Khalifa told AP news agency there had been no warning: "We only heard multiple F-16 [warplane] missiles, one after the other, six or seven missiles."
Israeli Prime Minister Benjamin Netanyahu praised the "superior intelligence" of the domestic Shin Bet security service and the "precise execution" of the attack.
"Operation Protective Edge will continue until its objective has been fulfilled - the restoration of long-term quiet for the citizens of Israel while causing significant damage to terrorist infrastructure," he said.
The three commanders killed were key to operations including smuggling, tunnel construction and capturing the Israeli soldier Gilad Shalit in 2006, the BBC's Yolande Knell reports.
Hamas commanders killed
- Raed al-Attar, the most senior Hamas commander in the south, personally handed over Israeli soldier Gilad Shalit to the Egyptians during the 2011 prisoner exchange; his role in Hamas was to smuggle weapons into the Gaza Strip and oversee recruitment and arms in the Rafah region, according to Israel
- Mohammed Abu Shamala was the Rafah commander said to have been responsible for planning the capture of Mr Shalit; he was also accused by Israel of killing an army officer in 1994 and orchestrating an attack in 2004 which killed six soldiers
- Mohammed Barhoum, a close relative of Hamas spokesman Fawzi Barhoum, was a senior local Hamas commander
"The assassinations of the three Qassam [Hamas military wing] leaders is a grave crime," Hamas spokesman Sami Abu Zuhri told Reuters news agency. "But it will not break our people and Israel will pay the price for it."
Israel's military said it had carried out 20 attacks on targets in Gaza during the night in response to militant rocket attacks. Since talks on extending the ceasefire failed, 213 rockets had been fired at Israel, it added.
In another development, Hamas warned foreign airlines to stop flying to and from Tel Aviv's Ben Gurion Airport from Thursday.
Hamas also confirmed it was abandoning efforts to negotiate a durable ceasefire with Israel.
It had gone to the talks in Cairo demanding an end to the Israeli and Egyptian blockades of Gaza, and the establishment of a seaport and airport.
Israel, for its part, had sought guarantees that Hamas and other factions in Gaza would be disarmed.
The UN Security Council voiced "grave concern" at the resumption of hostilities and "called upon the parties to resume negotiations to urgently reach a sustainable and lasting ceasefire".
Gaza officials say a total of 54 Palestinians have been killed since the temporary ceasefire broke down.