Israeli Prime Minister Benjamin Netanyahu has ordered "massive strikes" on the Gaza Strip after two-day escalation that killed 24 Palestinians and four Israelis.

Israeli warplanes and gunboats continued to target the Gaza Strip on Sunday as fighters in the besieged enclave fired a barrage of rockets into southern Israel.

A 34-year-old Hamas commander was killed in what the Israeli military described as a targeted strike. An army statement accused Hamad al-Khodori of "transferring large sums of money" from Iran to armed factions in Gaza.

He was the fifth Palestinian reported killed on Sunday. Other Palestinian victims included two pregnant women and three infants.

In the Israeli city of Ashkelon, a 58-year-old Israeli man was killed after being struck by shrapnel from a rocket attack. Two other Israelis, critically wounded in a separate rocket attacks on a factory on Sunday afternoon, later died.

"This morning I instructed the IDF [the Israeli Army] to continue with massive strikes against terrorists in the Gaza Strip," Netanyahu, who doubles as Israeli defence minister, said in a statement after consulting with his security cabinet on Sunday.

He said he had also ordered "tanks, artillery and infantry forces" to reinforce troops already deployed near Gaza, a move that raised fears of a ground invasion.

"Hamas is responsible not only for its attacks against Israel, but also for the Islamic Jihad's attacks, and it is paying a very heavy price for it," Netanyahu added.

A Palestinian man sits on the debris of a building that was destroyed in Israeli air attacks in Gaza City.

Armed factions in Gaza, otherwise known as the Joint Operations Room, which include the military wing of Hamas and the Islamic Jihad Movement in Palestine, vowed on Saturday to "extend its response" if the Israeli army continued to target the strip.

"Our response will be broader and more painful in the event [Israel's] extends in aggression, and we will remain the protective shield of our people and our land," the Joint Operations Room said in a statement.

Al Jazeera's Harry Fawcett, reporting from the Israeli side of the fence with Gaza, said the escalation was "far from over".

"This is potentially a dangerous and long, major military escalation," he said. "The Israeli media is quoting senior defence sources as saying they expect this fighting to last some days."

Israeli media reported Gaza fighters over the past two days fired more than 400 rockets at towns and cities in southern Israel and that the Israeli Iron Dome anti-missile system had intercepted more than 250 of them.

The government media office in Gaza said Israeli warplanes carried out about 150 raids, in addition to artillery-shelling targeting 200 civilian landmarks in the Gaza Strip, including residential buildings, mosques, shops and media institutions.

About 70 Palestinians were wounded in the attacks, according to Gaza's health ministry.

Gaza resident Um Alaa Abu Absa spent Sunday picking up broken glass and debris inside her property in the aftermath of the air raids.

"There was a lot of bombing, the neighbours were affected a lot, the street scene was indescribable, people were afraid and terrified and running, and everyone was looking for their children, nobody was able to see others," Abu Absa said.

One of the buildings destroyed had housed the Gaza bureau of the Turkish state-run Anadolu news agency.

"We call on the international community to act swiftly in order to ease tensions that have increased due to Israel's disproportionate actions in the region," a Turkish foreign ministry statement said.

The damaged al-Gussin apartment building after Israeli air raids in Gaza City [Anadolu Agency]

On Sunday, the Israeli army denied that Falastine Abu Arar, the 37-year-old pregnant mother, and her 14-month old niece Siba, were killed by Israeli forces. Instead it blamed a misfiring of a Palestinian rocket.

Two Palestinian men, 22-year-old Imad Nseir and 25-year-old Khaled Abu Qaleeq, were also killed by Israeli air raids on Saturday night.

The Palestinian Islamic Jihad group said the two men killed overnight on Sunday, Mahmoud Issa, 26 and Fawzi Bawadi, 23, were members of its armed wing.

In the early afternoon, two more Palestinians were killed after an Israeli air raid targeted a group of people in the eastern Gaza City neighbourhood of Shujayea, the health ministry said. The men were identified as Bilal Mohammed al-Banna and Abdullah Abu Atta, said to be in their 20s.

Shortly after, in what Palestinians have called the first targeted assassination since 2014, Israeli air raids hit the car of al-Khoudary, the Hamas commander, in Gaza City. Three other Palestinians were wounded on the attack. (Aljazeera)

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