Gaza militants fired new barrages of rockets at Israel on Sunday in a deadly escalation that has seen Israel respond with waves of strikes as a fragile truce again faltered, sparking fears of further violence.
Gazan authorities reported six Palestinians killed in Israeli strikes in the latest round of fighting that began Saturday, including at least two militants.
But Israel disputed their account of the deaths of a pregnant mother and her baby, blaming errant Hamas fire.
One 58-year-old Israeli man was killed overnight by a rocket strike on the city of Ashkelon near the Gaza border, Israeli police and the hospital said.
The latest flare-up came as Hamas, the Islamist movement that rules the blockaded Gaza Strip, sought further concessions from Israel under a fragile months-old ceasefire.
Israel said 450 rockets or mortars had been fired by Hamas and Islamic Jihad since Saturday and its air defences intercepted more than 150 of them.
As well as the Israeli man killed, an 80-year-old woman was seriously injured in a rocket strike on the Israeli city of Kiryat Gat, police and medics said.
A man was also hospitalised in Ashkelon, said police, citing other injuries without providing details.
A house near Ashkelon was damaged, while other rockets hit open areas.
The Israeli army said its tanks and planes hit some 220 militant targets in Gaza in response.
They included an Islamic Jihad attack tunnel that stretched from southern Gaza into Israeli territory, it said.
Two multi-storey buildings in Gaza City were also destroyed.
Israel said one of the buildings included Hamas military intelligence and security offices.
Israel said the other building housed Hamas and Islamic Jihad offices.
Six dead in Gaza
The Gaza health ministry said Israeli strikes killed a 14-month-old baby and her pregnant mother, 37, as well as four Palestinian men.
But Israeli army spokesman Jonathan Conricus said that based on intelligence "we are now confident" that the deaths of the mother and baby were not due to an Israeli strike.
Islamic Jihad identified two of the dead men as its militants. The ministry said 47 other people were also wounded.
As the exchange of fire continued, Israeli Prime Minister Benjamin Netanyahu held consultations with security chiefs on Saturday.
Netanyahu said on Sunday he ordered the military to continue "massive strikes" against militants in Gaza.
A statement on Saturday from Hamas ally Islamic Jihad claimed responsibility for at least some of the rocket fire and said it was prepared for more.
Its armed wing distributed a video showing militants handling rockets and threatening key Israeli sites, including Ben-Gurion international airport near Tel Aviv.
Israel closed its crossings with Gaza for people and goods as well as the zone it allows for fishermen off the enclave until further notice due to the rocket fire.
Egyptian and UN officials were engaged in discussions to calm the situation, as they have done repeatedly in the past, while the European Union called for an immediate halt to rocket fire from Gaza.
The UN envoy for the Israeli-Palestinian conflict, Nickolay Mladenov, called on "all parties to immediately de-escalate and return to the understandings of the past few months."
The United States condemned the rocket fire from Gaza and said it fully supported Israel's "right to self-defence against these abhorrent attacks."
Visit to Cairo
The escalation follows Friday clashes along the Gaza border that were the most violent in weeks.
Four Palestinians, including two Hamas militants, were killed after two Israeli soldiers were wounded in a shooting during weekly protests on the frontier.
Israel and Palestinian militants in the Gaza Strip have fought three wars since 2008 and fears remain of a fourth.
A ceasefire between Israel and Hamas, brokered by Egypt and the United Nations, had led to relative calm around Israel's April 9 general election.
But the past week saw a gradual uptick in violence.
With the ceasefire at risk, a Hamas delegation led by its Gaza head Yahya Sinwar went to Cairo on Thursday for talks with Egyptian officials.
The truce has seen Israel allow Qatar to provide millions of dollars in aid to Gaza to pay salaries and to finance fuel purchases to ease a severe electricity shortage.
Palestinians have participated in regular demonstrations and clashes along the Gaza border for more than a year, calling on Israel to ease its crippling blockade of the enclave.
At least 273 Palestinians have been killed by Israeli fire since the protests began in March 2018, the majority along the border.
Two Israeli soldiers and one civilian have been killed in that period.
Israel accuses Hamas of using the protests as cover to carry out attacks and says its actions are necessary to defend the border and stop infiltrations.